JP4374913B2 - Light emitting device - Google Patents

Description

【００９７】
（ＨＦＡ）_３Ｔｂ（ＴＰＰＯ）_２は、例えば酢酸テルビウムを出発原料とし、中心金属をＴｂとする。紫外線領域の光で励起され緑色系の発光が観測できる。また、上記（ＨＦＡ）_３Ｅｕ（ＴＰＰＯ）_２は、赤色系の発光をするため、（ＨＦＡ）_３Ｔｂ（ＴＰＰＯ）_２や緑色系の発光をする他の有機蛍光体ともに波長変換部材中に含有させることによって、該波長変換部材が白色系の混色光を発光するようにすることもできる。透光性無機部材の材料に均一に溶解する有機蛍光体は、上述したＹＡＧ系蛍光体や窒化物系蛍光体のような粒子状蛍光体と異なり、薄膜での波長変換部材の形成が可能であり、波長変換部材中で沈降することなく一様に分散して存在させることができる。さらに、発光素子の保護膜作成工程の中で、発光素子の保護膜としての機能も兼ね備えた波長変換部材を発光素子表面に形成し、波長変換部材の形成工程を簡略化することができる。
［発光素子］
本実施の形態において使用される発光素子は、例えばＬＥＤチップである。蛍光体と発光素子とを組み合わせて、蛍光体を励起させることによって波長変換した光を出光させる発光装置とする場合、蛍光体を励起可能な波長の光を出光するＬＥＤチップが使用される。ＬＥＤチップは、ＭＯＣＶＤ法等により基板上にＧａＡｓ、ＩｎＰ、ＧａＡｌＡｓ、ＩｎＧａＡｌＰ、ＩｎＮ、ＡｌＮ、ＧａＮ、ＩｎＧａＮ、ＡｌＧａＮ、ＩｎＧａＡｌＮ等の半導体を発光層として形成させる。半導体の構造としては、ＭＩＳ接合、ＰＩＮ接合やＰＮ接合などを有するホモ構造、ヘテロ構造あるいはダブルへテロ構成のものが挙げられる。半導体層の材料やその混晶度によって発光波長を種々選択することができる。また、半導体活性層を量子効果が生ずる薄膜に形成させた単一量子井戸構造や多重量子井戸構造とすることもできる。好ましくは、蛍光体を効率良く励起できる比較的短波長を効率よく発光可能な窒化物系化合物半導体（一般式Ｉｎ_iＧａ_jＡｌ_kＮ、ただし、０≦ｉ、０≦ｊ、０≦ｋ、ｉ＋ｊ＋ｋ＝１）である。
【００９８】
窒化ガリウム系化合物半導体を使用した場合、半導体基板にはサファイア、スピネル、ＳｉＣ、Ｓｉ、ＺｎＯ、ＧａＮ等の材料が好適に用いられる。結晶性の良い窒化ガリウムを形成させるためにはサファイア基板を用いることがより好ましい。サファイア基板上に半導体膜を成長させる場合、ＧａＮ、ＡｌＮ等のバッファ層を形成しその上にＰＮ接合を有する窒化ガリウム半導体を形成させることが好ましい。また、サファイア基板上にＳｉＯ₂をマスクとして選択成長させたＧａＮ単結晶自体を基板として利用することもできる。この場合、各半導体層の形成後ＳｉＯ₂をエッチング除去させることによって発光素子とサファイア基板とを分離させることもできる。窒化ガリウム系化合物半導体は、不純物をドープしない状態でＮ型導電性を示す。発光効率を向上させるなど所望のＮ型窒化ガリウム半導体を形成させる場合は、Ｎ型ドーパントとしてＳｉ、Ｇｅ、Ｓｅ、Ｔｅ、Ｃ等を適宜導入することが好ましい。一方、Ｐ型窒化ガリウム半導体を形成させる場合は、Ｐ型ドーパンドであるＺｎ、Ｍｇ、Ｂｅ、Ｃａ、Ｓｒ、Ｂａ等をドープさせる。
【００９９】
窒化ガリウム系化合物半導体は、Ｐ型ドーパントをドープしただけではＰ型化しにくいためＰ型ドーパント導入後に、炉による加熱、低速電子線照射やプラズマ照射等によりアニールすることでＰ型化させることが好ましい。具体的な発光素子の層構成としては、窒化ガリウム、窒化アルミニウムなどを低温で形成させたバッファ層を有するサファイア基板や炭化珪素上に、窒化ガリウム半導体であるＮ型コンタクト層、窒化アルミニウム・ガリウム半導体であるＮ型クラッド層、Ｚｎ及びＳｉをドープさせた窒化インジュウムガリウム半導体である活性層、窒化アルミニウム・ガリウム半導体であるＰ型クラッド層、窒化ガリウム半導体であるＰ型コンタクト層が積層されたものが好適に挙げられる。ＬＥＤチップを形成させるためにはサファイア基板を有するＬＥＤチップの場合、エッチングなどによりＰ型半導体及びＮ型半導体の露出面を形成させた後、半導体層上にスパッタリング法や真空蒸着法などを用いて所望の形状の各電極を形成させる。ＳｉＣ基板の場合、基板自体の導電性を利用して一対の電極を形成させることもできる。
【０１００】
次に、形成された半導体ウエハ等をダイヤモンド製の刃先を有するブレードが回転するダイシングソーにより直接フルカットするか、又は刃先幅よりも広い幅の溝を切り込んだ後（ハーフカット）、外力によって半導体ウエハを割る。あるいは、先端のダイヤモンド針が往復直線運動するスクライバーにより半導体ウエハに極めて細いスクライブライン（経線）を例えば碁盤目状に引いた後、外力によってウエハを割り半導体ウエハからチップ状にカットする。このようにして窒化物系化合物半導体であるＬＥＤチップ１０２を形成させることができる。ここで、本発明では特に波長変換部材を形成させた後にカットを行うことができる。発光素子と該発光素子からの発光が蛍光体により波長変換された光との混色光の光学特性を半導体ウエハ状態で行うことができるため、所望の発光特性を有する発光装置を歩留まりよく形成することができる。
【０１０１】
蛍光体を励起させて発光させる本発明の発光装置においては、蛍光体との補色等を考慮してＬＥＤチップの主発光波長は３５０ｎｍ以上５３０ｎｍ以下が好ましい。
［導電性ワイヤ９１１］
発光素子の固定方法としては、発光素子の少なくとも一方の電極をリード電極にそれぞれ対向させ導電部材を介して電気的に接続させる方法や、発光素子の基板側を接着剤により固定し発光素子の電極を導電性ワイヤによりリード電極と接続する方法を用いることができる。後者の方法を採用した場合、例えば、発光素子チップをエポキシ樹脂等にて一方のリード電極上にダイボンド固定した後、発光素子チップの各電極とリード電極とをそれぞれ導電性ワイヤにて接続する。導電性ワイヤとしては、ＬＥＤチップの電極とのオーミック性、機械的接続性、電気伝導性及び熱伝導性がよいものが求められる。熱伝導度としては０．０１ｃａｌ／（ｓ）（ｃｍ^２）（℃／ｃｍ）以上が好ましく、より好ましくは０．５ｃａｌ／（ｓ）（ｃｍ^２）（℃／ｃｍ）以上である。また、作業性などを考慮して導電性ワイヤの直径は、好ましくは、Φ１０μｍ以上、Φ４５μｍ以下である。特に、蛍光体が含有された波長変換部材と蛍光体が含有されていないモールド部材との界面で導電性ワイヤが断線しやすい。それぞれ同一材料を用いたとしても蛍光体が入ることにより実質的な熱膨張量が異なるため断線しやすいと考えられる。そのため、導電性ワイヤの直径は、２５μｍ以上がより好ましく、発光面積や扱い易さの観点から３５μｍ以下がより好ましい。
【０１０２】
このような導電性ワイヤとして具体的には、金、銅、白金、アルミニウム等の金属及びそれらの合金を用いた導電性ワイヤが挙げられる。このような導電性ワイヤは、各ＬＥＤチップの電極と、インナー・リード及びマウント・リードなどと、をワイヤーボンディング機器によって容易に接続させることができる。
［モールド部材］
モールド部材は、発光ダイオードの用途に応じてＬＥＤチップ、導電性ワイヤ、波長変換部材などを外部環境から保護するために設けることができる。モールド部材は、一般には樹脂を用いて形成させることができる。また、蛍光体を含有させることによって視野角を増やすことができるが、樹脂モールドに拡散剤を含有させることによってＬＥＤチップからの指向性を緩和させ視野角をさらに増やすことができる。更にまた、モールド部材を所望の形状にすることによってＬＥＤチップからの発光を集束させたり拡散させたりするレンズ効果を持たせることができる。従って、モールド部材は複数積層した構造でもよい。具体的には、凸レンズ形状、凹レンズ形状さらには、発光観測面から見て楕円形状やそれらを複数組み合わせた物である。モールド部材の具体的材料としては、主としてエポキシ樹脂、ユリア樹脂、シリコーン樹脂などの耐候性に優れた透明樹脂や硝子などが好適に用いられる。特に、上述したガラス質の透光性無機部材にてモールド部材を形成する場合は、ゾル溶液の粘度を調節することにより形成可能である。また、拡散剤としては、チタン酸バリウム、酸化チタン、酸化アルミニウム、酸化珪素、二酸化珪素等が好適に用いられる。さらに、拡散剤に加えてモールド部材中にも蛍光体を含有させることもできる。したがって、蛍光体はモールド部材中に含有させてもそれ以外の波長変換部材などに含有させて用いてもよい。また、波長変換部材を蛍光体が含有された透光性無機部材、モールド部材を透光性樹脂などと、異なる材料にて形成させても良い。この場合、生産性良くより水分などの影響が少ない発光装置とすることができる。また、屈折率差を小さくすることを考慮してモールド部材と波長変換部材とを同じ材料を用いて形成させても良い。本願発明においてモールド部材に拡散剤や着色剤を含有させることは、発光観測面側から見た蛍光体の着色を隠すことができる。なお、蛍光体の着色とは、本願発明の蛍光体が強い外光からの光のうち、青色成分を吸収し発光する。そのため黄色に着色しているように見えることである。特に、凸レンズ形状などモールド部材の形状によっては、着色部が拡大されて見えることがある。このような着色は、意匠上など好ましくない場合がある。モールド部材に含有された拡散剤は、モールド部材を乳白色に着色剤は所望の色に着色することで着色を見えなくさせることができる。したがって、このような発光観測面側から蛍光体の色が観測されることはない。
【０１０３】
また、ＬＥＤチップから放出される光の主発光波長が４３０ｎｍ以上では、光安定化剤である紫外線吸収剤をモールド部材中に含有させた方が耐候性上より好ましい。
以下、本発明に係る実施例について詳述する。なお、本発明は以下に示す実施例のみに限定されないことは言うまでもない。
【０１０４】
【実施例１】
図１は、本実施例にかかる発光素子の模式的断面図を示し、図２は、本実施例にかかる波長変換部材の孔版印刷による形成方法を模式的に示す。
【０１０５】
図１に示すように、本実施例にかかる発光素子は、発光素子であるＬＥＤチップ１００のサファイア基板１０２の表面に波長変換部材１０１が形成されている。ＬＥＤチップ１００は、発光層として単色性発光ピークが可視光である４７５ｎｍのＩｎ_０．２Ｇａ_０．８Ｎ半導体を有する窒化物半導体発光素子を用いる。より具体的には、ＬＥＤチップ１００は、洗浄させたサファイア基板上にＴＭＧ（トリメチルガリウム）ガス、ＴＭＩ（トリメチルインジウム）ガス、窒素ガス及びドーパントガスをキャリアガスと共に流し、ＭＯＣＶＤ法で窒化物半導体を成膜させることにより形成させることができる。ドーパントガスとしてＳｉＨ_４とＣｐ_２Ｍｇを切り替えることによってｎ型窒化物半導体やｐ型窒化物半導体となる層を形成させる。
【０１０６】
ＬＥＤチップ１００の素子構造としては、サファイア基板１０２上に、アンドープの窒化物半導体であるｎ型ＧａＮ層、Ｓｉドープのｎ型電極が形成されｎ型コンタクト層となるＧａＮ層、アンドープの窒化物半導体であるｎ型ＧａＮ層、次に発光層を構成するバリア層となるＧａＮ層、井戸層を構成するＩｎＧａＮ層、バリア層となるＧａＮ層を１セットとしＧａＮ層に挟まれたＩｎＧａＮ層を５層積層させた多重量子井戸構造としてある。発光層上にはＭｇがドープされたｐ型クラッド層としてＡｌＧａＮ層、Ｍｇがドープされたｐ型コンタクト層であるＧａＮ層を順次積層させた構成としてある。（なお、サファイア基板１０２上には低温でＧａＮ層を形成させバッファ層とさせてある。また、ｐ型半導体は、成膜後４００℃以上でアニールさせてある。）次に、エッチングによりサファイア基板１０２上の窒化物半導体に同一面側で、ｐｎ各コンタクト層表面を露出させる。各コンタクト層上に、スパッタリング法を用いて正負各台座電極をそれぞれ形成させる。なお、ｐ型窒化物半導体上の全面には金属薄膜を透光性電極として形成させた後に、透光性電極の一部に台座電極を形成させる。
【０１０７】
次に、波長変換部材中１０１に分散させて含有させる蛍光物質を形成する。本実施例における蛍光物質は、Ｙ、Ｇｄ、Ａｌ、及びＣｅのそれぞれの酸化物を化学量論比により混合し混合原料を得る。これにフラックスを混合して坩堝に詰め、ボールミル混合機にて２時間混合する。ボールを取り除いた後、弱還元雰囲気中１４００℃〜１６００℃にて６時間焼成し、更に還元雰囲気中１４００℃〜１６００℃にて６時間焼成する。焼成品を水中でボールミルして、洗浄、分離、乾燥、最後に篩を通して中心粒径が８μｍである（Ｙ_０．８Ｇｄ_０．２）_{２．７５０}Ａｌ_５Ｏ_１２：Ｃｅ_{０．２５０}蛍光物質を形成する。
【０１０８】
安定剤として硝酸を添加したアルミナゾル溶液１００重量部に対して、上記蛍光物質を１５０重量部添加した混合液を粘度調整し、蛍光体が混合液中で均一に分散するように調整する。
【０１０９】
半導体ウエハの基板面側にステンレス製孔版を配置する。このとき、孔版は、後の工程で発光素子毎に分割するのを容易にするため、基板上面上のスクライブライン形成位置をマスクし、発光素子の基板面の一部が露出するような貫通孔がメッシュ状に設けられている。孔版を配置後、混合液を孔版の貫通孔内に充填することにより孔版印刷を行い乾燥させる。乾燥は、室温にて自然乾燥を１時間、温度１００℃にて１０分間、温度２００℃〜２５０℃にて３０分間行う。このような乾燥を行うことにより、波長変換部材の割れを防止することができる。また、波長変換部材に対してサファイア基板上への十分な接着力を与えることができる。
【０１１０】
最終的に蛍光体が含有されたアルミナゾル溶液が硬化し、発光観測方位によって均一な膜厚数十μｍの波長変換部材１０１が発光素子のサファイア基板１０２上面に形成される。
【０１１１】
サファイア基板１０２上面に波長変換部材１０１が積層された半導体ウエハにスクライブラインを引いた後、外力により発光素子毎に分割する。このように波長変換部材が形成された発光素子は、サファイア基板側から、発光層からの光と蛍光体により波長変換された光との混色光を発光することができる。
【０１１２】
最後に、波長変換部材１０１が形成された発光素子１００の電極１０４、１０５を実装基板に設けられた導電性パターンに対向させ、導電性部材にて電気的に接続する。さらに、発光素子１００および波長変換部材１０１を樹脂で被覆することにより発光装置を形成する。
【０１１３】
以上のように形成される本実施例の発光装置において、ＬＥＤチップから出光した光の一部が波長変換部材に含有される蛍光物質により波長変換され、モールド部材から出光する混色光は観測方位によって均一に観測される。また、透光性無機部材が割れにくい厚さに形成されているため、信頼性の高い発光装置とすることができる。
【実施例２】
本実施例では、図３および図４に示されるように、窒化物系蛍光体（Ｓｒ_０．７Ｃａ_０．３）_２Ｓｉ_５Ｎ_８：Ｅｕを含有する波長変換部材を形成した後、該波長変換部材の上に実施例１と同様にＹＡＧ系蛍光体である（Ｙ_０．８Ｇｄ_０．２）_{２．７５０}Ａｌ_５Ｏ_１２：Ｃｅ_{０．２５０}蛍光物質を含有する波長変換部材を形成する。ここで、上記窒化物蛍光体は、上記ＹＡＧ系蛍光体の発光スペクトルのピーク波長領域に広い吸収スペクトル領域を有している。
【０１１４】
まず、窒化物系蛍光体（Ｓｒ_０．７Ｃａ_０．３）_２Ｓｉ_５Ｎ_８：Ｅｕを含有するアルミナゾル溶液を材料として半導体ウエハの基板側に対して孔版印刷を行う。このとき、窒化物蛍光体を含有する波長変換部材を形成するための第一の孔版１１１は、発光素子毎に分割するのを容易にするため、基板上面上のスクライブライン形成位置をマスクし、また、発光素子の基板面の一部が露出するような貫通孔が設けられている。窒化物蛍光体を含有する波長変換部材１０１を形成した後、第一の孔版１１１をそのまま配置し、第一の孔版１１１と貫通孔の位置を同じくした状態で第二の孔版１１２を第一の孔版１１１の上に配置する。次に、窒化物蛍光体を含有する波長変換部材１０１の上に（Ｙ_０．８Ｇｄ_０．２）_{２．７５０}Ａｌ_５Ｏ_１２：Ｃｅ_{０．２５０}蛍光物質を含有する波長変換部材１０３を形成する。波長変換部材１０３を形成した後、第一の孔版１１１および第二の孔版１１２を取り除き、発光素子毎にカットすることにより、図３に示されるような発光素子２００とすることができる。
【０１１５】
最後に、波長変換部材が形成された発光素子２００の電極１０４、１０５を実装基板に設けられた導電性パターンに対向させ、電気的に接続する。さらに、発光素子２００および波長変換部材１０１、１０３を樹脂で被覆することにより発光装置を形成する。
【０１１６】
このように複数の蛍光体を組み合わせることにより、ＹＡＧ系蛍光体により波長変換された光が窒化物系蛍光体に吸収されることがなくなり、発光素子と蛍光体との混色光の演色性を向上させた発光装置とすることができる。また、透光性無機部材が割れにくい厚さに形成されているため、信頼性の高い発光装置とすることができる。
【実施例３】
図５は、本実施例にかかる発光素子３００を模式的に示す断面図である。発光素子の電極が形成されている位置にマスクを施し、他の実施例と同様に孔版印刷を行うことにより、発光素子の電極が形成されている面および側方端面に対して、発光観測方位によって均一な膜厚の波長変換部材を形成する。導電性ワイヤにて発光素子の電極とリード電極とを接続し、波長変換部材、発光素子および導電性ワイヤをモールド部材で被覆することにより発光装置を形成する。本実施例の構成とすることにより、発光素子と蛍光体との混色光が発光観測面方向において均一に観測される発光装置とすることができる。また、透光性無機部材が割れにくい厚さに形成されているため、信頼性の高い発光装置とすることができる。
【実施例４】
図９から図１８は、本実施例にかかる発光素子９１０の製造工程を模式的に示す断面図である。図１８に示されるような波長変換部材１０１を有する発光素子９１０を作成する。以下、図９から図１８を参照しながら工程順に発光素子９１０の作成方法を説明する。
【０１１７】
サブマウント基板９０２の表面に導電性部材９０１を配置し（図９）、正電極と負電極とを分離する絶縁部９０４を有する導電性パターンとする（図１０）。
【０１１８】
サブマウント基板９０２の材料は、半導体発光素子と熱膨張係数がほぼ等しいもの、例えば窒化物半導体発光素子に対して窒化アルミニウムが好ましい。このような材料を使用することにより、サブマウント基板９０２と発光素子９００との間に発生する熱応力を緩和することができる。あるいは、サブマウント基板９０１の材料は、ｐ型半導体領域おおびｎ型半導体領域を有する保護素子として形成可能であり、比較的放熱性がよく安価でもあるシリコンが好ましい。また、導電性部材９０１は、反射率の高い銀や金、アルミニウムを使用することが好ましい。
【０１１９】
発光装置の信頼性を向上させるため、発光素子９００の正負両電極間と絶縁部９０４との間に生じた隙間にはアンダフィル材９０５が充填される。まず、上記サブマウント基板９０２の絶縁部９０４の周辺にアンダフィル材９０５が配置される（図１１）。アンダフィル材９０５は、例えばシリコーン樹脂やエポキシ樹脂等の熱硬化性樹脂である。アンダフィル材９０５の熱応力を緩和させるため、さらに窒化アルミニウム、酸化アルミニウム及びそれらの複合混合物等がエポキシ樹脂に混入されてもよい。アンダフィルの量は、発光素子の正負両電極間とサブマウント基板９０２との間に生じた隙間を埋めることができる量である。
【０１２０】
発光素子９００の正負両電極をサブマウント基板９０２に設けた上記導電性パターンの正負両電極にそれぞれ対向させ、バンプ９０６にて接合し固定する（図１２）。なお、サブマウントを保護素子としたときは、発光素子の正電極および負電極と保護素子のｎ型半導体領域およびｐ型半導体領域とをそれぞれ接続する。まず、発光素子の正負両電極に対して導電性部材であるバンプ９０６を形成する。なお、サブマウント基板９０２の導電性パターンの正負両電極に対してバンプ９０６を形成してもよい。サブマウント基板９０２の絶縁部９０４付近に配したアンダフィル材９０５が軟化しているとき（図１１）、発光素子９００の正負両電極が、バンプ９０６を介して上記導電性パターンの正負両電極と対向される。次に、荷重、熱および超音波により発光素子の正負両電極、バンプ９０６および上記導電性パターンは熱圧着される。このとき、バンプ９０６と上記導電性パターンの正負両電極との間のアンダフィルは排除され、発光素子の電極と上記導電性パターンの導通が図られる。導電性部材であるバンプ９０６の材料は、例えばＡｕ、共晶ハンダ（Ａｕ−Ｓｎ）、Ｐｂ−Ｓｎ、鉛フリーハンダ等である。
【０１２１】
発光素子の基板側からスクリーン版９０７を配置する（図１３）。なお、スクリーン版９０７の代わりとして、導電性ワイヤ９１１のボールボンディング位置やパーティングライン形成位置等、波長変換部材１０１を形成させない位置にメタルマスクを配置しても構わない。
【０１２２】
チキソ性を有するアルミナゾルに蛍光体を含有させた材料を調整し、スキージ（へら）９０８を使ってスクリーン印刷を行う（図１４）。
【０１２３】
スクリーン板９０７を取り外し（図１５）、蛍光体を含有させた材料を硬化させ（図１６）、パーティングラインに沿って発光素子毎にカットする（図１７）と、波長変換部材１０１を有する発光素子９１０が完成する（図１８）。
【０１２４】
さらに、図１９、図２０および図２１（図２０のＡＡ‘における断面図）に示されるように、上記発光素子９１０をパッケージ９１２の凹部底面９１３にＡｇペーストを接着剤として固定し、導電性ワイヤ９１１にて凹部底面９１３に一部露出させたリード電極９１４とサブマウント基板９０２に設けた導電性パターンとを接続して発光装置とすることができる。ここで、本実施例における発光装置は、発光装置の配光性を制御するためのレンズ９１５、および発光素子の放熱性を向上させ、発光素子を載置するための凹部底面が一部に形成される金属基体９１６を有する。また、レンズ９１５の下面とパッケージ９１２の凹部の内壁面との隙間にはシリコーン樹脂等のモールド部材を配置することが好ましい。このように構成することにより、発光素子からの光の取り出しを向上させ、信頼性の高い発光装置とすることができる。
【０１２５】
本実施例における発光装置は、波長変換部材中に含有された蛍光物質の含有量や分布がほぼ均一であり、発光装置ごとに色度、光量等の光学特性のバラツキが生じにくい。また、発光装置の形成工程や発光装置の構成部材に無駄を生じさせることなく、所望の発光装置を均一に形成することができるため、量産性に優れる。
【実施例５】
図７は、本実施例に係る発光装置の模式的な断面図である。図７に示されるように、本実施例にかかる波長変換部材の積層体は、発光素子の側から第一の層７０１と、第二の層７０２と、該第二の層と屈折率の異なる第三の層７０３とを発光素子に対して順に積層してなる。第一の層７０１は、イットリアを主成分とする透光性無機部材（屈折率；ｎ_１＝１．８）により窒化物系蛍光体が結着されてなる。該第一の層７０１は、砲弾型のレンズ形状を有するドットの集合体として、発光素子の基板側へストライプ状、格子状あるいは同心円状に多数配列してなる。また、第二の層７０２は、イットリアを主成分とする透光性無機部材（屈折率；ｎ_２＝１．８）からなり、第三の層７０３は、アルミナを主成分とする透光性無機部材（屈折率；ｎ_３＝１．７）によりアルミニウム・ガーネット系蛍光体が結着されてなる。さらに、本実施例にかかる波長変換部材の積層体における第一の層７０１は、該第一の層７０１により波長変換された光が第二の層７０２と第三の層７０３との界面において全反射されない方向へ進行するように光学制御するレンズ形状を有する。即ち、第一の層７０１から出射した光は、第二の層７０２と第三の層７０３によって形成される界面の臨界角θ_０（θ_０＝ｓｉｎ^−１ｎ_３／ｎ_２＝ｓｉｎ^−１０．９４）より小さい角度で界面に入射するように進行方向を制御される。従って、発光素子（屈折率２．５）の基板１０２の側から出光した光は、第一の層７０１に含有される窒化物系蛍光体により波長変換され、該波長変換された光は、第二の層７０２と第三の層７０３との界面において全反射されることなく発光観測面方向から出射し観測される。
【０１２６】
このように構成することにより、第一の層７０１から出光する光は、第二の層７０２と第三の層７０２の界面において全反射されることがなく、発光観測面方向とは異なる方向へ進行することが抑制されるため、波長変換された光の取り出し効率を向上させることができる。
【０１２７】
【発明の効果】
本発明は、蛍光体の含有量および分布を均一とさせた発光装置を製造歩留まりよく容易に得ることができる。ガラス等の比較的割れやすい透光性無機部材を材料として波長変換部材を形成する際、透光性無機部材を割れ難い厚さに形成することが容易にできる。また、波長変換部材中に含有された蛍光物質の含有量や分布がほぼ均一となるため、発光装置ごとに色度、光量等の光学特性のバラツキが生じにくくなり、発光装置の製造歩留まりが向上する。また、励起吸収スペクトルや発光スペクトルの異なる複数種の蛍光体を混合させることなく、複数種の蛍光体をそれぞれ含有する多層な波長変換部材を形成することにより、発光装置から出光する混色光の演色性を良好にすることができる。また、工程や発光装置の構成部材に無駄を生じさせることなく、作業性よく所望の発光装置を形成することができる。
【０１２８】
【図面の簡単な説明】
【図１】 図１は、本発明の一実施例にかかる発光素子の模式的な断面図である。
【図２】 図２は、本発明の一実施例にかかる波長変換部材の形成方法を示す模式図である。
【図３】 図３は、本発明の一実施例にかかる発光素子の模式的な断面図である。
【図４】 図４は、本発明の一実施例にかかる波長変換部材の形成方法を示す模式図である。
【図５】 図５は、本発明の一実施例にかかる発光素子の模式的な断面図である。
【図６】 図６は、本発明の一実施例にかかる発光素子の模式的な上面図である。
【図７】 図７は、本発明の一実施例にかかる発光素子の模式的な断面図である。
【図８】 図８は、本発明の一実施例にかかる発光素子の模式的な断面図である。
【図９】 図９は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１０】 図１０は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１１】 図１１は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１２】 図１２は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１３】 図１３は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１４】 図１４は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１５】 図１５は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１６】 図１６は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１７】 図１７は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１８】 図１８は、本発明の一実施例にかかる形成工程を示す模式的な断面図である。
【図１９】 図１９は、本発明の一実施例にかかる発光装置の模式的な断面図である。
【図２０】 図２０は、本発明の一実施例にかかる発光装置の模式的な上面図である。
【図２１】 図２１は、本発明の一実施例にかかる発光装置の模式的な断面図である。
【図２２】 図２２は、本発明の一実施例にかかる発光素子の模式的な上面図である。
【符号の説明】
１００、２００、３００、９００、１３１・・・発光素子、１０１、１０３、１３２・・・波長変換部材、１０２・・・半導体発光素子基板、１０４・・・正電極、１０５・・・負電極、１０６・・・孔版、１０７・・・透光性無機部材、１０８・・・へら、１０９・・・蛍光体、１１０・・・マスクとなる側壁、１１１・・・第一の孔版、１１２・・・第二の孔版、７０１、８０１・・・第一の層、７０２・・・第二の層、７０３・・・第三の層、９０１・・・導電性部材、９０２・・・サブマウント基板、９０３・・・パーティングライン、９０４・・・絶縁部、９０５・・・アンダフィル材、９０６・・・バンプ、９０７・・・スクリーン版、９０８・・・スキージ、９０９・・・波長変換部材の形成材料、９１０・・・波長変換部材を形成した発光素子、９１１・・・導電性ワイヤ、９１２・・・パッケージ、９１３・・・凹部底面、９１４・・・リード電極、９１５・・・レンズ、９１６・・・金属基体。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a light emitting device used for an illumination light source, an LED display, a backlight light source, a traffic light, an illuminated switch, various sensors, various indicators, and the like, and a method for forming the same.
[0002]
[Prior art]
  In recent years, a light-emitting device that is capable of obtaining white-color mixed light by combining a light-emitting element formed using a gallium nitride-based compound semiconductor and a phosphor that emits light by absorbing at least part of light from the light-emitting element. Devices are being developed and used. In these light-emitting devices, for example, a light-emitting element is placed on the bottom surface of a recess formed in a part of a support such as a mounting substrate, and a light-transmitting member filled in the recess further contains a fluorescent material. Thus, a wavelength conversion member is formed, and the wavelength conversion member is configured to cover the light emitting element. Such a wavelength conversion member is made by, for example, containing a fluorescent substance in a material of a translucent member such as an epoxy resin or glass, and then dropping and injecting it into a recess where a light emitting element is placed with a dispenser or the like. It is formed by curing (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
    Japanese Patent Laid-Open No. 7-99345.
[0004]
[Problems to be solved by the invention]
  However, the conventional light emitting device and the method for forming the wavelength conversion member have the following problems.
[0005]
  First, when forming a wavelength conversion member using a light-transmitting inorganic member such as glass as a material, forming the light-transmitting inorganic member that is relatively easy to crack with the above-described forming method such as potting has a thickness that is difficult to break. Even if it is going to do, control of the film thickness of a wavelength conversion member is very difficult. In addition, the above-described forming method such as potting is not easy to mold the wavelength conversion member into a shape that takes into consideration the light extraction efficiency, light distribution, and color mixing properties from the wavelength conversion member.
[0006]
  Second, if the content and distribution of the fluorescent material are different around the light emitting element, uniform light emission cannot be obtained depending on the light emission observation direction. This is because the fluorescent material contained in the wavelength conversion member greatly affects the amount of light emitted to the outside of the light-emitting device and the amount of light wavelength-converted by the phosphor depending on the content and distribution of the fluorescent material. In addition, if the content and distribution of the fluorescent material are different for each light emitting device, variations in optical characteristics such as chromaticity and light amount occur for each light emitting device, and the manufacturing yield of the light emitting device is reduced.
[0007]
  Third, when various phosphors having different excitation absorption spectra and emission spectra are mixed and contained in the wavelength conversion member, there is a problem that light converted in wavelength by one phosphor is absorbed by another phosphor. This affects the optical properties such as the color rendering properties of the mixed color light emitted from the light emitting device. Considering the characteristics of such phosphors, even if the wavelength conversion members containing different phosphors are arranged in a preferred form by the above-described formation method by potting, the wavelength conversion members are evenly arranged according to the emission observation direction. It is difficult to do.
[0008]
  Fourth, after the light emitting element is placed in the recess, the light emitting device is formed through the step of covering the light emitting element with the wavelength conversion member, and only the light emitting device satisfying the desired light emission characteristics is obtained. Therefore, a desired light-emitting device cannot be formed with good workability.
[0009]
  Accordingly, an object of the present invention is to solve the above-described problems and easily obtain a light emitting device having a uniform phosphor content and distribution with a high production yield.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, a light-emitting device according to the present invention is a light-emitting device that includes a light-emitting element and a wavelength conversion member that absorbs light from the light-emitting element and emits different wavelengths. The member is composed of a translucent inorganic member and a phosphor.In order from the light emitting element side, at least a first layer, a second layer, and a third layer having a refractive index smaller than that of the second layer are laminated, and the first layer Is arranged in the light emitting element as an assembly of bullet-shaped lens shapes that make incident light incident on the interface at an angle smaller than the critical angle at the interface between the second layer and the third layer. It is characterized by being.
[0011]
  With this configuration, in consideration of the light resistance of the light-emitting device, the wavelength conversion member made of a light-transmitting inorganic member such as glass is formed into a thickness and shape that is difficult to break, and a highly reliable light-emitting device is obtained. Can do. Further, the fluorescent substance contained in the wavelength conversion member can have a constant content and distribution of the fluorescent substance depending on the emission observation direction, and uniform light emission can be obtained depending on the emission observation direction of the light emitting device.
[0012]
  The wavelength conversion member is formed by sequentially laminating at least a first layer, a second layer, and a third layer having a refractive index different from that of the second layer from the light emitting element side. This layer has a lens shape. The lens shape may have a shape that controls light distribution in a direction in which the light emitted from the nth (n ≧ 1) layer is not totally reflected at the interface between the (n + 1) th layer and the (n + 2) th layer. If comprised in this way, the extraction efficiency of the light which permeate | transmits a 2nd layer, or the light which is wavelength-converted by a 2nd layer and radiate | emits this 2nd layer will improve. Further, uniform light emission can be obtained depending on the light emission observation direction of the light emitting device.
[0013]
  The wavelength conversion member may be laminated on the light emitting element via a buffer layer containing at least one component element of the translucent inorganic member. With this structure, the adhesion between the stacked body and the light-emitting element is improved, so that a highly reliable light-emitting device can be obtained.
[0014]
  The first layer and the second layer contain phosphors having different compositions and / or different types of translucent inorganic members, respectively. If comprised in this way, it can be set as the light-emitting device which can light-emit color mixing light of the light from a light emitting element, and the fluorescence by various fluorescent substance. In addition, in consideration of absorption / light emission characteristics between the phosphors, a light emitting device in which wavelength conversion members are stacked in an order that improves the optical characteristics of the light emitting device can be obtained.
[0015]
  The translucent inorganic member may be made of an oxide hydroxide or hydroxide containing at least one group IIIA element and group IIIB element. With this configuration, a wavelength conversion member that is not colored and deteriorated even by high-output light can be obtained, so that a highly reliable light-emitting device can be obtained.
[0016]
  The oxide hydroxide or hydroxide includes crystal water. The translucent inorganic member is made of a hydroxide, oxide hydroxide or oxide containing at least Al. The translucent inorganic member is made of a hydroxide, oxide hydroxide or oxide containing at least Y. The translucent inorganic member further contains boron oxide or boric acid. With this configuration, a wavelength conversion member that is not colored and deteriorated even by higher-power light can be obtained, so that a more reliable light-emitting device can be obtained.
[0017]
  At least one of the phosphors includes N and includes at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, Sn, Ti, Zr, and Hf. A phosphor including at least one selected element and activated with at least one element selected from rare earth elements may be used. If comprised in this way, it can be set as the light-emitting device which can light-emit the color mixing light of the fluorescence by nitride type fluorescent substance, and the light emission from a light emitting element.
[0018]
  At least one of the phosphors contains Al and includes at least one element selected from Y, Lu, Sc, La, Gd, Tb, Eu and Sm, and one element selected from Ga and In. It is good also as the fluorescent substance containing and activated with the at least 1 element selected from the rare earth elements. If comprised in this way, it can be set as the light-emitting device which can light-emit mixed-color light with the fluorescence by an aluminum garnet type fluorescent substance, the light emission from a light emitting element, or the fluorescence by a nitride type fluorescent substance.
[0019]
  Furthermore, the method for forming a light-emitting device of the present invention includes a light-emitting device and a wavelength conversion member containing a phosphor that emits light having a different wavelength by absorbing at least part of the light from the light-emitting device. A first step of adjusting a mixture of a sol solution for producing a translucent inorganic member and the phosphor, and uniformly dispersing the phosphor in the mixture; and A second step of applying and curing the light emitting element, and the second step is repeatedly performed on the light emitting element wafer or the light emitting element placed on the support substrate. . With such a formation method, a light emitting device in which the phosphor content and distribution are uniform can be easily obtained with a high manufacturing yield. The second step is a stage in which the light emitting element is in a state of a semiconductor wafer and / or a state in which the light emitting element is placed on a submount wafer that is chipped as a support substrate. Therefore, a desired light-emitting device can be formed with good workability without causing waste in processes and components of the light-emitting device. Furthermore, the second step is performed a plurality of times on the same wafer, thereby adjusting the film thickness of the wavelength conversion member and preventing the translucent member included in the wavelength conversion member from cracking.
[0020]
  The second step is performed on the substrate surface of the light emitting element that has been subjected to laser irradiation or VUV irradiation. By adopting such a forming method, it is possible to easily improve the adhesion between the wavelength conversion member and the semiconductor wafer surface.
[0021]
  The two steps are performed on a light emitting element provided with a buffer layer containing at least one component element of the sol solution. By adopting such a formation method, the adhesion between the wavelength conversion member and the light emitting element can be improved, and a highly reliable light emitting element can be obtained.
[0022]
  The second step is performed with a plurality of types of phosphors having different compositions. When formed in this way, it is possible to easily form a light emitting device in which different types of wavelength conversion members are stacked in order so that the optical properties of the light emitting device are improved in consideration of the absorption and emission characteristics of various phosphors.
[0023]
  The second step is performed by a mixture of plural kinds containing sol solutions having different compositions. By forming in this way, it is possible to easily form a multilayer wavelength conversion member having a different refractive index.
[0024]
  The sol solution is a sol solution of a compound containing at least one element selected from Group IIIA elements and Group IIIB elements. By forming the light-emitting device in this way, a wavelength conversion member that is not colored and deteriorated even by high-power light can be obtained, so that a highly reliable light-emitting device can be easily obtained.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a light emitting device for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device to the following. Further, the size and positional relationship of the members shown in the drawings are exaggerated for clarity of explanation.
[0026]
  In a conventional light emitting device having a phosphor and a light emitting element, the light emitting element is placed on the bottom surface of the cup that reflects light emitted from the light emitting element in the direction of the light emission observation surface, and the resin filled in the cup is separated from the light emitting element. The light emitting element is covered as a wavelength conversion member containing a fluorescent substance that absorbs at least a part of light and converts the wavelength to emit fluorescence. Such a wavelength conversion member is formed by dripping and injecting a resin material containing a fluorescent substance into a cup on which a light emitting element is placed, using a dispenser or the like, and thermosetting the resin material.
[0027]
  However, according to the above formation method, it is not easy to drop and inject a light-transmitting inorganic member such as glass with a dispenser or the like instead of the resin material, and to harden the film to a thin film that is difficult to break.
[0028]
  Moreover, even if the wavelength conversion member by said formation method is dripped in the same amount of the resin material containing the fluorescent substance, it is the same for each light emitting device up to the amount of phosphor contained and its distribution state. It is difficult. Therefore, variations in optical characteristics such as chromaticity occur among the light emitting devices, and the manufacturing yield of the light emitting devices is reduced. In particular, when the wavelength conversion member containing each of a plurality of types of phosphors having different compositions is formed in multiple layers, the distribution state of the phosphors in each layer is different for each layer, and further for each light emitting device, The variation in the optical characteristics of each light emitting device becomes even more remarkable.
[0029]
  Therefore, the present inventors are a light-emitting device having a light-emitting element and a wavelength conversion member containing a phosphor that emits light having a different wavelength by absorbing at least part of the light from the light-emitting element, In particular, the wavelength conversion member includes the phosphor and the light-transmitting inorganic member, and is a layered, striped, latticed, concentric, dot-shaped or a combination of at least two of these shapes with respect to the light emitting element. As a result, the problems related to the light emitting device as described above have been solved. That is, each phosphor is bound by a separate light-transmitting inorganic member and laminated in layers to form a wavelength conversion member having a multiple structure. When the wavelength conversion member is configured as a multiple thin film in this way, the red phosphor layer, the green phosphor layer, and the blue phosphor layer are stacked in this order on the light emitting element in consideration of the light transmittance of each phosphor. In all layers, the excitation light can be absorbed evenly. In addition, each wavelength conversion member including each phosphor is arranged in a stripe shape, a lattice shape, a triangle shape, or a dot shape so as to obtain desired optical characteristics. Moreover, you may make it arrange | position by providing a space | interval between each wavelength conversion member, and, thereby, color mixing property can be made favorable. Furthermore, if the wavelength conversion member is formed so as to cover the entire periphery of the element, the wavelength conversion can be performed without leaking light from the element, so that the wavelength conversion efficiency by the phosphor is improved, and when ultraviolet light is used as excitation light It is preferable because ultraviolet light leakage can be prevented.
[Embodiment 1]
  1 and 3 are schematic cross-sectional views of the light-emitting element according to the present embodiment. 2 and 4 are cross-sectional views schematically showing the method for forming the light emitting element according to this embodiment. 22A to 22D show light emitting elements in which the wavelength conversion member 132 is formed in a stripe shape (a), a lattice shape (b), a concentric circle shape (c), and a dot shape (d), respectively. 3 is a schematic top view illustrating 131. FIG. Hereinafter, the present embodiment will be described in more detail with reference to the drawings.
[0030]
  As shown in FIG. 1, the light-emitting device according to the present embodiment has a wavelength conversion member 101 formed by, for example, stencil printing on the surface of the light-emitting element on the substrate 102 side. The wavelength conversion member 101 shown in FIG. 1 has a layered cross section, but when viewed from the substrate 102 side of the light emitting element, it is striped (shown in FIG. 22A), latticed (FIG. 22B). The wavelength conversion member may be arranged by combining the shapes so as to form a triangle shape or a dot shape (shown in FIG. 22D). The coating method in the present invention is not limited to stencil printing, and may be ink jet coating, spin coating and spray coating, or various coating methods combining at least one of them. In the light-emitting elements 100 and 200 according to the present embodiment, a pair of positive and negative electrodes of the light-emitting element are opposed to a conductive pattern provided on the surface of the submount substrate or a lead electrode inserted in the support. By electrically connecting to the light emitting device, a light emitting device as shown in FIGS. 20 and 21 can be obtained.
[0031]
  As shown in FIG. 3, the light emitting device 300 according to the present embodiment includes wavelength conversion members 101 and 103 on the substrate 102 side of the light emitting device, each containing phosphors having different compositions and laminated in multiple layers. .
[0032]
  In addition, as shown in FIG. 5, for example, the light emitting element 300 according to the present embodiment includes wavelength conversion members 101 and 103 formed on the electrode side surface and the side end surface excluding the position of the electrode of the light emitting element. Have Such a light-emitting element 300 can be a light-emitting device by fixing the substrate surface of the light-emitting element with respect to the mounting surface and connecting a pair of positive and negative electrodes to an external electrode or a lead electrode with a conductive wire.
[0033]
  Here, in the wavelength conversion member in the present invention, the phosphor is at least from the group of Al, Ga, Ti, Ge, P, B, Zr, Y, Sn, Pb, Gd, Lu, Sc, In or an alkaline earth metal. It is fixedly formed by a translucent inorganic member generated from a sol solution of a compound containing one or more selected elements. In addition, stencil printing in the present invention refers to a thin film forming method such as copying and screen printing. Furthermore, the stencil in the present invention refers to a mask that is used in a thin film forming method such as a copying plate or screen printing and has a through-hole formed in a mesh shape.
[0034]
  Furthermore, the present inventors prepared a first step of adjusting a mixture of a sol solution and a phosphor to produce a light-transmitting inorganic member, and uniformly dispersing the phosphor in the mixture, and the mixture as a light emitting device. A second step of applying and curing to the light emitting device, and the second step is repeatedly performed on the light emitting device in the wafer state or the light emitting device mounted on the wafer of the submount substrate. By adopting the method for forming a light emitting device, the problems relating to the above-described formation method have been solved. That is, the wavelength conversion member forming method according to the present invention is a forming method using a stencil as schematically shown in FIGS. 2 and 4, and includes at least the following steps 1 to 4. And
[0035]
  Step 1. Sol of a compound containing at least one element selected from the group of at least Al, Ga, Ti, Ge, P, B, Zr, Y, Sn, Pb, Gd, Lu, Sc, In or alkaline earth metal A first step of adjusting the viscosity of the mixture of the solution and the phosphor and uniformly dispersing the phosphor in the mixture.
[0036]
  In this step, at least one element selected from the group of Al, Ga, Ti, Ge, P, B, Zr, Y, Sn, Pb, Gd, Lu, Sc, In or alkaline earth metal is included. Examples of the compound include metal alkoxides such as aluminum alcoholate. In this step, a phosphor is contained in a sol solution or colloid solution of metal alkoxide, and gelation of the sol solution (in this specification, “gel” is a colloid composed of a solid and a liquid in which the sol loses its fluidity). The viscosity of the mixed solution is adjusted by adding a stabilizer that suppresses the system), and the phosphor is stirred in a state of being uniformly dispersed in the mixed solution. Here, in order to maintain the uniform dispersibility of the fluorescent substance, it is necessary to consider the specific gravity of the phosphor, but the viscosity is 5 × 10 5 with a B-type viscometer.³PS more than 1 × 10⁵PS or less is preferable, more preferably 9 × 10³PS over 3 × 10⁴PS or less. Thus, stencil printing can be performed with good workability by adjusting the viscosity. Further, the compound used in the present embodiment can easily impart thixotropy to the mixed solution by appropriately selecting the amount of the stabilizer and the kind of the sol solution and adjusting the solution viscosity. By using a mixed liquid having thixotropy, stencil printing can be performed with good workability.
[0037]
  Step 2. A second step in which a stencil patterned so as to obtain a desired shape such as a stripe shape, a lattice shape, a concentric shape, a spiral shape, a triangle shape, or a dot shape is fixedly arranged on the light emitting element;
[0038]
  A stencil provided with a pattern in a desired shape such as a stripe shape, a lattice shape, a concentric shape, a spiral shape, a triangle shape, or a dot shape is placed on the light emitting element. At this time, it is preferable to form a side wall 110 serving as a mask at a position where the wavelength conversion member is not desired to be placed, such as the position of the electrode of the light emitting element. Such a mask may be provided as a part of the stencil, and is removed together with the stencil after the wavelength conversion member is formed. Moreover, it is preferable to previously form a buffer layer containing at least one component element of the translucent member by a method such as sputtering on the light emitting element. By forming in this way, the wavelength conversion member can be a light emitting element laminated via a buffer layer containing at least one component element of the translucent member, and adhesion at the interface between the wavelength conversion member and the light emitting element Therefore, the wavelength conversion member can be prevented from peeling off. In addition, when the wavelength conversion member is formed on the substrate of the light emitting element, it is preferable to perform laser irradiation or VUV irradiation in advance on the substrate surface of the light emitting element. By forming the wavelength conversion member after performing the surface treatment in this manner, the adhesion between the wavelength conversion member and the substrate surface of the light emitting element is improved, so that the wavelength conversion member can be prevented from peeling off.
[0039]
  Step 3. A third step of injecting the mixture into the through-hole, covering at least the surface of the light-emitting element, and then curing.
[0040]
  The mixed liquid prepared in the first step is injected into the through-hole of the stencil while maintaining the uniform dispersion state of the phosphor to cover the surface of the light emitting element. For example, as shown in FIG. 2, the spatula 108 is moved in a direction parallel to the light emitting element substrate 102, thereby injecting the above mixed solution in the traveling direction of the spatula 108 into the through-hole, and the surface of the light emitting element substrate 102. Coating. And the liquid mixture is hardened by heat-drying. When the sol solution has thixotropy, the phosphor can be maintained in a uniform dispersed state and can be easily injected into a through-hole provided in a mesh shape of a stencil and cured. In this step, it is preferable to repeat the stencil printing and curing steps until the film thickness of the wavelength conversion member reaches a desired film thickness. When forming a wavelength conversion member with a translucent inorganic member, the present invention can be formed by easily controlling a relatively fragile translucent inorganic member to a film thickness that is difficult to break. In addition, after the formation of the first wavelength conversion member is completed, each layer is converted to a different wavelength by using a large number of mixed liquids containing phosphors having different compositions and materials of different types of translucent inorganic members. Or a light emitting device having a multilayer wavelength conversion member having a different refractive index for each layer. In addition, the nth (n ≧ 1) wavelength conversion can be achieved by using various stencils with patterns in desired shapes such as stripes, lattices, concentric circles, spirals, triangles, dots, etc. The shape of the member and the (n + 1) th wavelength conversion member provided thereon can be made different. Moreover, even if the stencils have the same pattern, the arrangement of the stencils with respect to the light emitting elements (semiconductor wafers) is made different so that, for example, a multilayer structure having a desired shape is obtained, such as a stripe shape in which different types of phosphors are alternately arranged. be able to.
[0041]
  Step 4. Furthermore, the wavelength conversion member according to the present invention is formed at a stage before the light emitting element is divided into chips, that is, in the state of the wafer of the light emitting element, or a supporting substrate (for example, a submount) that supports the mounted light emitting element. It can be performed on the wafer before being divided into chips as the substrate), that is, on the wafer of the support substrate. For example, as shown in FIG. 2 or FIG. 4, the wavelength conversion member can be formed on the surface of the semiconductor light emitting element substrate 102 when the semiconductor wafer is divided into chips as light emitting elements. . Further, as shown in FIG. 14, the wavelength conversion member is formed on the upper surface of the submount after the light emitting element is placed on the submount substrate in the wafer state and then divided into chips as the submount substrate. It is also possible to cover the periphery of the light emitting element.
[0042]
  A conventional method for forming a light-emitting device including a phosphor and a light-emitting element includes a step of covering the light-emitting element with a wavelength conversion member after placing the light-emitting element in a recess formed in a part of a support. In this method, a light emitting device is formed, and the light emitting characteristics are inspected at the final stage of the process to obtain only the light emitting device satisfying the desired optical characteristics. Therefore, the process spent on the light emitting device that does not satisfy the desired optical characteristics and the components of the light emitting device are wasted. In addition, variation in optical characteristics occurs between the light emitting elements, and a light emitting element having uniform optical characteristics cannot be obtained with high productivity. On the other hand, in the forming method according to the present invention, the wavelength conversion member is formed at the wafer stage before the light emitting element or the submount substrate is cut for each chip, and the recess formed in a part of the support such as a package. Since the light emission characteristics are inspected before being placed in the light emitting device, a light emitting device having uniform desired optical characteristics can be formed with high productivity without causing waste of processes and components. Moreover, when laminating | stacking a wavelength conversion member in order with a 1st layer, a 2nd layer, ..., n-th layer (n> = 1) from the light emitting element side, the wavelength conversion member of the 1st layer is made for every light emitting element. After the light emitting device formed at the stage of the semiconductor wafer before being cut into the first and second wavelength conversion members is fixed to the support or the submount, the second wavelength conversion member is formed. You can also
[Embodiment 2]
  The wavelength conversion member in this embodiment includes a phosphor and a light-transmitting inorganic member, and has at least two layers, stripes, lattices, concentric circles, spirals, dots, or these shapes with respect to the light emitting element. In particular, the stacked body is formed by stacking an nth (n ≧ 1) layer and an (n + 1) th layer in order from the light emitting element side, and the nth layer includes the nth layer. It has a lens shape that optically controls so that the light wavelength-converted by the layer travels in a direction where it is not totally reflected at the interface between the (n + 1) th layer and the (n + 2) th layer. That is, the light emitted from the nth layer proceeds so as to be incident on the interface between the (n + 1) th layer and the (n + 2) th layer at an angle smaller than the critical angle θ due to the lens shape of the nth layer. The direction is controlled. In the present embodiment, the phosphor is contained in the nth layer, but the phosphor may not be contained in the nth layer. In this case, the nth layer has a lens shape that optically controls so that light traveling from the light emitting element side does not undergo wavelength conversion and travels in a direction in which it is not totally reflected at the interface between the (n + 1) th layer and the (n + 2) th layer. Have
[0043]
  The present embodiment will be described in more detail based on FIGS. For example, as shown in FIG. 7, the wavelength conversion member in the light emitting device of this embodiment includes the first layer 701, the second layer 702, and the refractive index of the second layer 702 from the substrate 102 side of the light emitting element. A third layer 703 having different layers is sequentially stacked on the light emitting element. Further, the first layer 701 collects light in which the wavelength converted by the phosphor contained in the first layer 701 is not totally reflected at the interface between the second layer 702 and the third layer 703. It has a lens shape. On the other hand, in the wavelength conversion member shown in FIG. 8, the first layer 801, the second layer 702, and the third layer 703 having a refractive index different from that of the second layer emit light sequentially from the substrate 102 side of the light emitting element. It becomes a laminated body laminated | stacked on the element in layers.
[0044]
  As shown in FIG. 7 or FIG. 8, the second layer 702 and the third layer 703 constituting the wavelength conversion member laminate are configured so that the refractive index gradually decreases from the light emitting element side. Thus, the light extraction efficiency from the light emitting element is improved. Here, the third layer having a refractive index different from that of the second layer is easily formed by appropriately adjusting the kind of the sol solution for forming the light-transmitting inorganic member or the composition of the phosphor contained therein. .
[0045]
  However, in the wavelength conversion member formed by laminating layers having different refractive indexes as shown in FIG. 8, the critical angle θ at the interface between the second layer 702 and the third layer 703.₀Light from the first layer 701 may enter the interface at a larger angle. In this case, as shown by arrows, total reflection of light traveling from the light emitting element side occurs at the interface between the second layer 702 and the third layer 703 having different refractive indexes, and light emitted from the light emission observation surface direction. The percentage of decrease. Therefore, in the wavelength conversion member in the present embodiment, as shown in FIG. 7, the first layer 701 formed immediately before the interface has a specific lens shape, and the light traveling from the light emitting element side, Or it is set as the structure which condenses the light wavelength-converted by the 1st layer 701 in a predetermined direction, and radiate | emits it from a wavelength conversion member.
[0046]
  With this configuration, the light emitted from the first layer 701 constituting the wavelength conversion member is totally reflected at the interface between the second layer and the third layer, or is in a direction different from the emission observation surface direction. The light extraction efficiency from the light emitting device can be improved.
[0047]
  Hereafter, each structure in embodiment of this invention is explained in full detail.
[Wavelength conversion member]
  The wavelength conversion member in the present invention includes a phosphor that converts light emitted from the LED chip into light having different wavelengths, and a translucent inorganic member that binds the phosphor, and is layered, striped, or latticed These are provided around the light emitting element as concentric circles, spiral shapes, dot shapes, or a laminate obtained by combining at least two of these shapes.
(Translucent inorganic member)
  The translucent inorganic member in the present invention is a material that binds phosphors to each other or around the light emitting element, and is a material that constitutes a part of the wavelength conversion member. Specific examples of the material for binding the phosphor around the light emitting device include transparent resins having excellent weather resistance such as epoxy resin, urea resin, and silicone resin. In the present invention, gelation of silica sol is generated. Further, a light-transmitting inorganic member such as an alumina sol or yttria sol gel product excellent in light resistance, glass or the like is preferably used.
[0048]
  In the conventional configuration in which the phosphor is dispersed in the resin, since most of the resin is deteriorated by the ultraviolet rays contained in the blue light, it is not possible to constitute an element that can withstand long-term use. It was further difficult to put into practical use a white light emitting device using a light emitting element that emits light. On the other hand, a wavelength conversion member in which a phosphor is bound (bound) by a translucent inorganic member formed according to the present invention is an inorganic substance, unlike a conventional resin. Degradation due to is extremely small as compared with resin, and can be used in combination with a light emitting device that emits ultraviolet light.
[0049]
  The specific main material of the wavelength conversion member in the present invention is an amorphous metal oxide, an ultrafine metal oxide, dispersed in water or an organic solvent uniformly with a small amount of inorganic acid, organic acid and alkali as a stabilizer. A sol solution is used. As starting materials for synthesizing amorphous metal oxides and ultrafine metal oxides, metal alcoholates, metal diketonates, metal halides, metal carboxylic acids, hydrolysates of metal alkyl compounds, and mixed and hydrolyzed Things can be used. Also, use a colloid (sol) solution in which metal hydroxide, metal chloride, metal nitrate, metal oxide fine particles are uniformly dispersed in water, an organic solvent, or a mixture of water and a water-soluble organic solvent. Can do.
[0050]
  Further, the wavelength conversion member may contain a diffusing agent together with the phosphor. Specific examples of the diffusing agent include barium titanate, titanium oxide, aluminum oxide, silicon oxide, silicon dioxide, zirconium oxide, yttrium oxide, a mixture containing one or more of these oxides, or a composite oxide of the above metal element components, etc. Are preferably used.
[0051]
  Hereinafter, the case where an aluminum compound or a yttria compound is used as a translucent inorganic member will be described as an example.
[0052]
  Examples of metal alcoholates include aluminum methoxide, aluminum ethoxide, aluminum-n-propoxide, aluminum isopropoxide, aluminum-n-butoxide, aluminum-sec-butoxide, aluminum-iso-propoxide, aluminum-tert-butoxide, Yttrium methoxide, yttrium ethoxide, yttrium-n-propoxide, yttrium isopropoxide, yttrium-n-butoxide, yttrium-sec-butoxide, yttrium-iso-propoxide, yttrium-tert-butoxide and the like can be used.
[0053]
  Examples of metal diketonates include aluminum trisethyl acetoacetate, alkyl acetoacetate aluminum diisopropylate, ethyl acetoacetate aluminum diisopropylate, aluminum monoacetylacetonate-bisethylacetoacetate, aluminum trisacetylacetonate, yttrium trisacetylacetonate, Yttrium trisethyl acetoacetate can be used.
[0054]
  As the metal carboxylate, aluminum acetate, aluminum propionate, aluminum 2-ethylhexanoate, yttrium acetate, yttrium propionate, yttrium 2-ethylhexanoate, or the like can be used.
[0055]
  As the metal halide, aluminum chloride, aluminum bromide, aluminum iodide, yttrium chloride, yttrium bromide, yttrium iodide, or the like can be used.
[0056]
  As an organic solvent, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, tetrahydrofuran, dioxane, acetone, ethylene glycol, methyl ethyl ketone, N, N-dimethylformamide, N, N -Dimethylacetamide and the like can be used.
(Formation of wavelength conversion member)
  In the conventional method for forming a wavelength conversion member, the phosphor-containing material cannot be uniformly disposed on the entire surface of the light-emitting element, that is, on the upper surface, side surfaces, and corners. Were not uniformly distributed. Therefore, it has been difficult to convert the light emitted from the entire surface of the light emitting element to a wavelength with extremely high efficiency and extract it to the outside. On the other hand, in the formation method by stencil printing according to the present invention, a material containing a phosphor for a light emitting element in a wafer state, or a light emitting element placed on a wafer of a submount substrate, the entire surface of the light emitting element, that is, the upper surface, The same film thickness can be evenly arranged on the side and corner portions. Accordingly, the wavelength conversion member formed by binding the phosphor having the wavelength conversion function can be formed on the entire surface of the light emitting element, that is, the upper surface, the side surface, and the corner with the same film thickness. The phosphors are uniformly dispersed on the entire surface. As a result, it is possible to wavelength-convert light emitted from the entire surface of the light emitting element, that is, the upper surface, side surfaces, and corners with extremely high efficiency, and to uniformly extract the light to the outside.
[0057]
  A wavelength conversion member in which a phosphor is bound by a translucent inorganic member mainly composed of an aluminum compound is an aluminum sol obtained by mixing aluminum alcoholate or aluminum alkoxide with a high boiling point organic solvent at a predetermined ratio. After adjusting the coating liquid in which the phosphor (powder) is uniformly dispersed, the alumina sol in which the phosphor is dispersed is stencil-printed so as to cover the light extraction surface of the light emitting element, and then the alumina formed from the alumina sol Aluminum compounds contained in the gel (for example, alumina oxide hydroxide such as AlOOH, Al₂O₃Or Al (OH)₃) To fix the phosphors to each other and further to the surface of the light emitting element. Here, finally, the alumina sol becomes a mixture having aluminum oxide hydroxide as a main component and having a crosslinked structure with aluminum hydroxide or aluminum oxide (alumina).
[0058]
  Aluminum alcoholate or aluminum alkoxide is an organoaluminum compound used as a thickener for paints, a gelling agent, a coining agent, a polymerization catalyst, and a pigment dispersant. Aluminum alcoholate, or aluminum isopropoxide, aluminum ethoxide, and aluminum butoxide, which are a type of aluminum alkoxide, are highly reactive and produce aluminoxane polymers with moisture in the air, followed by heating. And aluminum oxide hydroxide with boehmite structure. For example, aluminum isopropoxide easily reacts with water, and finally becomes aluminum oxide hydroxide having amorphous alumina, pseudoboehmite, and boehmite structure. Here, the addition of a stabilizer such as nitric acid to aluminum isopropoxide allows easy control of the change from sol to gel state. It can be formed easily. Furthermore, after reacting aluminum isopropoxide with moisture in the air, the phosphor is bound with an aluminum compound generated by heating to support on the surface of the light emitting element and other than on the surface of the light emitting element. It can be formed on the body as a wavelength conversion member.
[0059]
  The material that can be used as the binder for fixing the phosphor is not limited to oxide hydroxides, oxides, and hydroxides containing Al or Y elements, but also includes at least one other group IIIA element or group IIIB element. Hydroxides, oxides, hydroxides and the like can be used. The metal element to be selected is preferably a trivalent stable metal element that hardly changes in valence. Moreover, it is preferable that an oxide hydroxide, an oxide, and a hydroxide contain crystal water. By comprising in this way, an oxide hydroxide, an oxide, and a hydroxide can exist stably. Furthermore, the translucent inorganic member preferably contains boron oxide or boric acid. By comprising in this way, it can be set as the translucent inorganic member which is hard to break. Moreover, it is more preferable that it is colorless and transparent. For example, a metal compound containing a metal element such as Gd, Lu, Sc, Ga, or In can be used. Alternatively, a composite oxide or a composite oxide hydroxide obtained by combining a plurality of these elements may be used. As described above, the wavelength conversion member formed of the translucent inorganic member having a constant valence, preferably a trivalent oxide hydroxide, obtained in the present embodiment is unlikely to cause an oxidation-reduction reaction and has high light resistance. It has a characteristic that it has no coloring deterioration. Therefore, the wavelength conversion member formed of the inorganic member has improved light extraction efficiency as compared with the prior art.
[0060]
  The wavelength conversion member in the present embodiment is at least Al, Ga, Ti, Ge, P, B, Zr, Y or an alkaline earth metal, like the wavelength conversion member in which the phosphor is bound by the aluminum compound described above. It can be formed by containing a phosphor in a sol solution in which one or more kinds of compounds containing one or more elements selected from the group, for example, one or more metal alkoxide compounds are mixed, gelled and dried.
[0061]
  The wavelength conversion member is only a wavelength conversion member in which the phosphor is bound by the compound generated from the alumina sol on the same light emitting element, or the wavelength conversion member in which the phosphor is bound by the compound generated from the various sol solutions. May be formed in multiple layers, or a wavelength conversion member composed of two or more layers may be formed on the same light emitting element. According to the method for forming a wavelength conversion member by stencil printing in the present invention, the film thickness of the wavelength conversion member is controlled by changing the thickness of the mask for stencil printing or by printing in multiple times. Therefore, it is possible to easily form a wavelength conversion member made of a translucent inorganic member having a film thickness that is difficult to break. Moreover, the wavelength conversion member of the same shape can be easily formed with respect to several light emitting elements. For example, on the same light emitting element, a wavelength conversion member is first formed using alumina sol as a material, and a wavelength conversion member is formed thereon using yttria sol as a material. Here, the phosphor may be included in both of the two layers, may be included in only one layer, or may not be included in both of the two layers. If the refractive index of the gallium nitride compound semiconductor and the refractive index of the wavelength conversion member generated from different types of sol solutions are reduced in the direction away from the surface of the light emitting element, the light extraction efficiency can be improved. Can do. This is because, when a sharp refractive index difference occurs at the interface between the wavelength conversion member and the outside air or the nitride semiconductor light emitting device, a part of the light extracted from the light emitting device may be reflected at the interface, so that the light extraction efficiency It is thought that this is likely to cause a decrease in
[Phosphor]
  The phosphor used in the present invention is contained in a wavelength conversion member together with a translucent inorganic member as a binder of the phosphor, and absorbs at least part of visible light and ultraviolet light emitted from the light emitting element. It is a substance for wavelength conversion to light having different wavelengths.
[0062]
  The phosphor used in the present invention refers to a phosphor that emits light when excited by at least light emitted from a light emitting element. In this embodiment, a phosphor that is excited by ultraviolet light and generates light of a predetermined color can be used as a phosphor. As a specific example, for example,
(1) Ca₁₀(PO₄)₆FCl: Sb, Mn
(2) M₅(PO₄)₃Cl: Eu (where M is at least one selected from Sr, Ca, Ba, Mg)
(3) BaMg₂Al₁₆O₂₇: Eu
(4) BaMg₂Al₁₆O₂₇: Eu, Mn
(5) 3.5MgO / 0.5MgF₂・ GeO₂: Mn
(6) Y₂O₂S: Eu
(7) Mg₆As₂O₁₁: Mn
(8) Sr₄Al₁₄O₂₅: Eu
(9) (Zn, Cd) S: Cu
(10) SrAl₂O₄: Eu
(11) Ca₁₀(PO₄)₆ClBr: Mn, Eu
(12) Zn₂GeO₄: Mn
(13) Gd₂O₂S: Eu, and
(14) La₂O₂S: Eu etc. are mentioned.
[0063]
  In addition, these phosphors may be contained in a single layer in a wavelength conversion member configured in multiple layers, or different types of phosphors may be mixed and contained. Furthermore, different types of phosphors may be contained in each layer alone or in combination.
[0064]
  When the light emitted from the light emitting element and the light emitted from the phosphor are in a complementary color relationship or the like, the light emitting device can emit white mixed light by mixing each light. Specifically, the light from the light emitting element and the phosphor light that is excited and emitted thereby correspond to the three primary colors of light (red, green, and blue), or the blue light emitted from the light emitting element. The light and the yellow light of the fluorescent substance excited and emitted by it are mentioned.
[0065]
  The emission color of the light-emitting device can be adjusted in various ways, such as the ratio of the phosphor to various resins that act as binders for the phosphor and inorganic members such as glass, the sedimentation time of the phosphor, and the shape of the phosphor. By selecting the emission wavelength, it is possible to provide an arbitrary white color tone such as a light bulb color. It is preferable that the light from the light emitting element and the light from the phosphor efficiently pass through the mold member outside the light emitting device.
[0066]
  The phosphor used in the present embodiment includes an aluminum garnet phosphor represented by an yttrium aluminum garnet phosphor (hereinafter sometimes referred to as “YAG phosphor”), and a red phosphor. It is possible to combine a phosphor capable of emitting the above light, particularly a nitride phosphor. These YAG-based phosphors and nitride-based phosphors can be separately contained in a wavelength conversion member composed of a plurality of layers. Hereinafter, each phosphor will be described in detail.
(Aluminum / garnet phosphor)
  The aluminum garnet phosphor used in the present embodiment includes Al and at least one element selected from Y, Lu, Sc, La, Gd, Tb, Eu, and Sm, and Ga and In. It is a phosphor that includes one selected element and is activated by at least one element selected from rare earth elements, and is a phosphor that emits light when excited by visible light or ultraviolet light emitted from a light emitting element. . For example, in addition to YAG phosphors, Tb_2.95Ce_0.05Al₅O₁₂, Y_2.90Ce_0.05Tb_0.05Al₅O₁₂, Y_2.94Ce_0.05Pr_0.01Al₅O₁₂, Y_2.90Ce_0.05Pr_0.05Al₅O₁₂Etc. In particular, in the present embodiment, two or more kinds of yttrium / aluminum oxide phosphors activated by Ce or Pr and having different compositions can be used. For example, YAlO₃: Ce, Y₃Al₅O₁₂Y: Ce (YAG: Ce) or Y₄Al₂O₉: Ce, and also a mixture thereof. Further, at least one of Ba, Sr, Mg, Ca, and Zn may be contained, and by further containing Si, the crystal growth reaction can be suppressed and the fluorescent substance particles can be aligned. Here, the YAG-based phosphor activated with Ce is to be interpreted in a broad sense, and part or all of yttrium is converted into at least one element selected from the group consisting of Lu, Sc, La, Gd, and Sm. It is substituted, or a part or all of aluminum is used in a broad sense including a phosphor having a fluorescent action in which any one or both of Ba, Tl, Ga, and In are substituted. More specifically, the general formula (Y_zGd_1-z)_ThreeAl_FiveO₁₂: Photoluminescence phosphor represented by Ce (where 0 <z ≦ 1) or a general formula (Re_1-aSm_a)_ThreeRe ’_FiveO₁₂: Ce (where 0 ≦ a <1, 0 ≦ b ≦ 1, Re is at least one selected from Y, Gd, La, Sc, and Re ′ is at least one selected from Al, Ga, In) The photoluminescence phosphor shown in FIG. The photoluminescence phosphor in the present embodiment can be two or more phosphors having different contents of Al, Ga, Y, Gd, and Sm.
[0067]
  Blue light emitted from a light emitting element using a nitride compound semiconductor in the light emitting layer and green light and red light emitted from a phosphor whose body color is yellow to absorb blue light, or When yellow light and green light and red light are mixedly displayed, a desired white light emission color display can be performed. In order to cause this color mixture, the light emitting device preferably contains phosphor powder or bulk in various resins such as epoxy resin, acrylic resin or silicone resin, and inorganic materials such as silicon oxide and aluminum oxide. Thus, the thing containing the fluorescent substance can be variously used according to uses, such as a dot-like thing and a layer-like thing formed so thinly that the light from the LED chip is transmitted. Arbitrary color tones such as a light bulb color including white can be provided by variously adjusting the ratio, coating, and filling amount of the phosphor and the resin, and selecting the emission wavelength of the light emitting element.
[0068]
  Further, by arranging two or more kinds of phosphors in order with respect to the incident light from the light emitting element, a light emitting device capable of emitting light efficiently can be obtained. That is, on a light emitting element having a reflective member, a wavelength conversion member containing a phosphor that has an absorption wavelength on the long wavelength side and can emit light at a long wavelength, and an absorption wavelength on the longer wavelength side that has a longer wavelength. The reflected light can be effectively used by laminating a wavelength conversion member capable of emitting light at a wavelength.
[0069]
  When a YAG phosphor is used, the irradiance is (Ee) = 0.1 W · cm^-21000W ・ cm^-2Even in the case where the following LED chips are in contact with or in close proximity to each other, a light-emitting device having sufficient light resistance can be obtained with high efficiency.
[0070]
  The cerium-activated yttrium / aluminum oxide phosphor used in the present embodiment, which is a green-based YAG phosphor capable of emitting light, has a garnet structure and is resistant to heat, light and moisture, and is excited and absorbed. The peak wavelength of the spectrum can be in the vicinity of 420 nm to 470 nm. Also, the emission peak wavelength λp is near 510 nm, and has a broad emission spectrum that extends to the vicinity of 700 nm. On the other hand, the YAG phosphor that emits red light, which is an yttrium-aluminum oxide phosphor activated by cerium, has a garnet structure, is resistant to heat, light and moisture, and has a peak wavelength of 420 nm in the excitation absorption spectrum. To about 470 nm. Further, the emission peak wavelength λp is in the vicinity of 600 nm, and has a broad emission spectrum that extends to the vicinity of 750 nm.
[0071]
  Of the composition of YAG phosphors with a garnet structure, the emission spectrum is shifted to the short wavelength side by substituting part of Al with Ga, and part of Y of the composition is replaced with Gd and / or La. By doing so, the emission spectrum shifts to the long wavelength side. Such a YAG-based phosphor can also be obtained, for example, by firing a raw material adjusted so as to add an excess of substitutional elements relative to the stoichiometric ratio. If the substitution of Y is less than 20%, the green component is large and the red component is small. On the other hand, at 80% or more, although the reddish component increases, the luminance rapidly decreases. Similarly, the excitation absorption spectrum is shifted to the short wavelength side by substituting part of Al with Ga in the composition of the YAG phosphor having a garnet structure. By substituting a part of Gd and / or La, the excitation absorption spectrum is shifted to the longer wavelength side. The peak wavelength of the excitation absorption spectrum of the YAG phosphor is preferably on the shorter wavelength side than the peak wavelength of the emission spectrum of the light emitting element. With this configuration, when the current input to the light emitting element is increased, the peak wavelength of the excitation absorption spectrum substantially matches the peak wavelength of the emission spectrum of the light emitting element, so that the excitation efficiency of the phosphor is not reduced. Thus, a light emitting device in which the occurrence of chromaticity deviation is suppressed can be formed.
[0072]
  Such phosphors use oxides or compounds that easily become oxides at high temperatures as raw materials for Y, Gd, Ce, La, Al, Sm and Ga, and mix them well in a stoichiometric ratio. And get the raw materials. Alternatively, a coprecipitated oxide obtained by co-precipitation of a solution obtained by coprecipitation of a solution obtained by dissolving a rare earth element of Y, Gd, Ce, La, and Sm in an acid at a stoichiometric ratio with oxalic acid, and aluminum oxide or gallium oxide. To obtain a mixed raw material. Fluoride such as ammonium fluoride or NH as flux₄A suitable amount of Cl is mixed and packed in a crucible, fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a fired product, and then the fired product is ball-milled in water for washing, separation, drying, Finally, it can be obtained by passing through a sieve. Further, in the method for producing a phosphor in another embodiment, a first firing step in which a mixture composed of a mixture of phosphor materials and a flux is mixed in the atmosphere or in a weak reducing atmosphere, and in a reducing atmosphere. It is preferable to perform the baking in two steps, which includes the second baking step performed in step (b). Here, the weak reducing atmosphere refers to a weak reducing atmosphere set to include at least the amount of oxygen necessary in the reaction process of forming a desired phosphor from the mixed raw material. By performing the first firing step until the formation of the phosphor structure is completed, blackening of the phosphor can be prevented and a decrease in light absorption efficiency can be prevented. In addition, the reducing atmosphere in the second firing step refers to a reducing atmosphere stronger than the weak reducing atmosphere. By firing in two stages in this way, a phosphor with high absorption efficiency at the excitation wavelength can be obtained. Therefore, when a light emitting device is formed with the phosphor thus formed, the amount of the phosphor necessary for obtaining a desired color tone can be reduced, and a light emitting device with high light extraction efficiency can be formed. Can do.
[0073]
  Yttrium / aluminum oxide phosphors activated with two or more types of cerium having different compositions may be used in combination, or may be arranged independently. When the phosphors are arranged independently, it is preferable to arrange the phosphors in the order of the phosphor that easily absorbs and emits light from the light emitting element on the shorter wavelength side and the phosphor that easily absorbs and emits light on the longer wavelength side. This makes it possible to efficiently absorb and emit light.
(Nitride phosphor)
  The first phosphor used in the present invention contains N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, Sn, Ti, A nitride-based phosphor including at least one element selected from Zr and Hf and activated by at least one element selected from rare earth elements. The nitride-based phosphor used in the present embodiment refers to a phosphor that emits light when excited by absorbing visible light, ultraviolet light, and light emitted from the YAG-based phosphor emitted from the LED chip 102. . In particular, the phosphor according to the present invention includes Sr—Ca—Si—N: Eu, Ca—Si—N: Eu, Sr—Si—N: Eu, and Sr—Ca—Si—O—N with Mn added: Eu, Ca-Si-ON: Eu, Sr-Si-ON: Eu-based silicon nitride. The basic constituent element of this phosphor is represented by the general formula L_XSi_YN_{(2 / 3X + 4 / 3Y)}: Eu or L_XSi_YO_ZN_{(2 / 3X + 4 / 3Y-2 / 3Z)}: Eu (L is Sr, Ca, or any one of Sr and Ca). In the general formula, X and Y are preferably X = 2, Y = 5, or X = 1, Y = 7, but any can be used. Specifically, Mn is added as a basic constituent element (Sr_XCa_1-X)₂Si₅N₈: Eu, Sr₂Si₅N₈: Eu, Ca₂Si₅N₈: Eu, Sr_XCa_1-XSi₇N₁₀: Eu, SrSi₇N₁₀: Eu, CaSi₇N₁₀: It is preferable to use a phosphor represented by Eu, but in the composition of this phosphor, from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr and Ni At least one or more selected may be contained. However, the present invention is not limited to this embodiment and examples.
L is any one of Sr, Ca, Sr and Ca. The mixing ratio of Sr and Ca can be changed as desired.
By using Si for the composition of the phosphor, it is possible to provide an inexpensive phosphor with good crystallinity.
[0074]
  Europium Eu, which is a rare earth element, is used for the emission center. Europium mainly has bivalent and trivalent energy levels. The phosphor of the present invention has Eu as a base material for alkaline earth metal silicon nitride.²⁺Is used as an activator. Eu²⁺Is easily oxidized and trivalent Eu₂O₃It is marketed with the composition. However, commercially available Eu₂O₃Then, the involvement of O is large, and it is difficult to obtain a good phosphor. Therefore, Eu₂O₃It is preferable to use a product obtained by removing O from the system. For example, it is preferable to use europium alone or europium nitride. However, this is not the case when Mn is added.
[0075]
  The additive Mn is Eu.²⁺Is promoted to improve luminous efficiency such as luminous brightness, energy efficiency, and quantum efficiency. Mn is contained in the raw material, or Mn alone or a Mn compound is contained in the manufacturing process and fired together with the raw material. However, Mn is not contained in the basic constituent elements after firing, or even if contained, only a small amount remains compared to the initial content. This is probably because Mn was scattered in the firing step.
The phosphor has at least one selected from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, O and Ni in the basic constituent element or together with the basic constituent element. Contains the above. These elements have actions such as increasing the particle diameter and increasing the luminance of light emission. Further, B, Al, Mg, Cr and Ni have an effect that afterglow can be suppressed.
[0076]
  Such a nitride-based phosphor absorbs part of the blue light emitted by the LED chip 102 and emits light in the yellow to red region. Using a nitride-based phosphor together with a YAG-based phosphor in the light-emitting device having the above-described configuration, the blue light emitted from the light-emitting element and the yellow to red light by the nitride-based phosphor are mixed to produce a warm color system. Provided is a light-emitting device that emits white light. It is preferable that the phosphor added in addition to the nitride-based phosphor contains an yttrium / aluminum oxide phosphor activated with cerium. This is because it can be adjusted to a desired chromaticity by containing the yttrium aluminum oxide phosphor. The yttrium / aluminum oxide phosphor activated with cerium absorbs part of the blue light emitted by the LED chip 102 and emits light in the yellow region. Here, the blue light emitted by the LED chip 102 and the yellow light of the yttrium / aluminum oxide fluorescent material emit light blue-white by mixing colors. Therefore, the yttrium / aluminum oxide phosphor and the phosphor emitting red light are mixed together in the wavelength conversion member 101 and combined with the blue light emitted by the LED chip 102 to produce white mixed light. A light-emitting device that emits light can be provided. Particularly preferred is a white light emitting device whose chromaticity is located on the locus of black body radiation in the chromaticity diagram. However, in order to provide a light emitting device having a desired color temperature, the amount of phosphor of the yttrium / aluminum oxide phosphor and the amount of phosphor of red light emission can be appropriately changed. This light-emitting device that emits white-based mixed color light improves the special color rendering index R9. A conventional light emitting device that emits white light only with a combination of a blue light emitting element and a yttrium aluminum oxide phosphor activated with cerium has a special color rendering index R9 of nearly 0 at a color temperature of Tcp = 4600K, The red component was insufficient. For this reason, increasing the special color rendering index R9 has been a problem to be solved. However, in the present invention, the special color rendering index near the color temperature Tcp = 4600K is obtained by using the phosphor emitting red light together with the yttrium aluminum oxide phosphor. R9 can be increased to around 40.
[0077]
  Next, the phosphor according to the present invention ((Sr_XCa_1-X)₂Si₅N₈: Eu) manufacturing method will be described, but is not limited to this manufacturing method. The phosphor contains Mn and O.
[0078]
  Raw materials Sr and Ca are pulverized. The raw materials Sr and Ca are preferably used alone, but compounds such as imide compounds and amide compounds can also be used. The raw materials Sr and Ca include B, Al, Cu, Mg, Mn, and Al.₂O₃Etc. may be contained. The raw materials Sr and Ca are pulverized in a glove box in an argon atmosphere. Sr and Ca obtained by pulverization preferably have an average particle diameter of about 0.1 μm to 15 μm, but are not limited to this range. The purity of Sr and Ca is preferably 2N or higher, but is not limited thereto. In order to improve the mixed state, at least one of the metal Ca, the metal Sr, and the metal Eu can be alloyed, nitrided, pulverized, and used as a raw material.
[0079]
  The raw material Si is pulverized. The raw material Si is preferably a simple substance, but a nitride compound, an imide compound, an amide compound, or the like can also be used. For example, Si₃N₄, Si (NH₂)₂, Mg₂Si and the like. The purity of the raw material Si is preferably 3N or higher, but Al₂O₃, Mg, metal boride (Co₃B, Ni₃B, CrB), manganese oxide, H₃BO₃, B₂O₃, Cu₂Compounds such as O and CuO may be contained. Si is also pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere in the same manner as the raw materials Sr and Ca. The average particle size of the Si compound is preferably about 0.1 μm to 15 μm.
[0080]
  Next, the raw materials Sr and Ca are nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 1 and formula 2, respectively.
[0081]
  3Sr + N₂  → Sr₃N₂  ... (Formula 1)
  3Ca + N₂  → Ca₃N₂  ... (Formula 2)
  Sr and Ca are nitrided in a nitrogen atmosphere at 600 to 900 ° C. for about 5 hours. Sr and Ca may be mixed and nitrided, or may be individually nitrided. Thereby, a nitride of Sr and Ca can be obtained. Sr and Ca nitrides are preferably of high purity, but commercially available ones can also be used.
[0082]
  The raw material Si is nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 3.
[0083]
            3Si + 2N₂  → Si₃N₄  ... (Formula 3)
  Silicon Si is also nitrided in a nitrogen atmosphere at 800 to 1200 ° C. for about 5 hours. Thereby, silicon nitride is obtained. The silicon nitride used in the present invention is preferably highly pure, but commercially available ones can also be used.
[0084]
  Sr, Ca or Sr—Ca nitride is pulverized. Sr, Ca, and Sr—Ca nitrides are pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere.
Similarly, Si nitride is pulverized. Similarly, Eu compound Eu₂O₃Crush. Europium oxide is used as the Eu compound, but metal europium, europium nitride, and the like can also be used. In addition, as the raw material N, an imide compound or an amide compound can be used. Europium oxide preferably has a high purity, but commercially available products can also be used. The average particle size of the alkaline earth metal nitride, silicon nitride and europium oxide after pulverization is preferably about 0.1 μm to 15 μm.
[0085]
  The raw material may contain at least one selected from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, O, and Ni. In addition, the above elements such as Mg, Zn, and B can be mixed by adjusting the blending amount in the following mixing step. These compounds can be added alone to the raw material, but are usually added in the form of compounds. This type of compound includes H₃BO₃, Cu₂O₃MgCl₂, MgO / CaO, Al₂O₃, Metal borides (CrB, Mg₃B₂, AlB₂, MnB), B₂O₃, Cu₂O, CuO, and the like.
[0086]
  After the pulverization, Sr, Ca, Sr—Ca nitride, Si nitride, Eu compound Eu₂O₃And add Mn. Since these mixtures are easily oxidized, they are mixed in a glove box in an Ar atmosphere or a nitrogen atmosphere.
[0087]
  Finally, Sr, Ca, Sr—Ca nitride, Si nitride, Eu compound Eu₂O₃The mixture is calcined in an ammonia atmosphere. Mn was added by firing (Sr_XCa_1-X)₂Si₅N₈: A phosphor represented by Eu can be obtained. However, the composition of the target phosphor can be changed by changing the blending ratio of each raw material.
[0088]
  For firing, a tubular furnace, a small furnace, a high-frequency furnace, a metal furnace, or the like can be used. The firing temperature can be in the range of 1200 to 1700 ° C, but the firing temperature is preferably 1400 to 1700 ° C. It is preferable to use a one-step baking in which the temperature is gradually raised and the baking is performed at 1200 to 1500 ° C. for several hours, but the first baking is performed at 800 to 1000 ° C. and the heating is gradually started from 1200. Two-stage firing (multi-stage firing) in which the second stage firing is performed at 1500 ° C. can also be used. The phosphor material is preferably fired using a boron nitride (BN) crucible or boat. In addition to the crucible made of boron nitride, alumina (Al₂O₃) Material crucible can also be used.
[0089]
  By using the above manufacturing method, it is possible to obtain a target phosphor.
[0090]
  In the present embodiment, a nitride-based phosphor has been particularly described as a phosphor that emits reddish light. However, in the present invention, red light can be emitted from the YAG-based phosphor described above. A light-emitting device including another phosphor can also be used. Such a phosphor capable of emitting red light is a phosphor that emits light when excited by light having a wavelength of 400 to 600 nm.₂O₂S: Eu, La₂O₂S: Eu, CaS: Eu, SrS: Eu, ZnS: Mn, ZnCdS: Ag, Al, ZnCdS: Cu, Al, and the like. Thus, by using a phosphor capable of emitting red light together with a YAG phosphor, it is possible to improve the color rendering properties of the light emitting device.
[0091]
  The phosphors capable of emitting red light typified by aluminum garnet phosphors and nitride phosphors formed as described above are disposed in a wavelength conversion member formed of a single layer around the light emitting element. Two or more types may exist, and one type or two or more types may exist in the wavelength conversion member consisting of two layers. With such a configuration, it is possible to obtain mixed color light by mixing light from different types of phosphors. In this case, it is preferable that the average particle diameters and shapes of the phosphors are similar in order to better mix the light emitted from the phosphors and reduce color unevenness. Further, the nitride phosphor may have an absorption spectrum over a wide wavelength region including the peak wavelength region of the emission spectrum of the aluminum garnet phosphor. In such a case, considering that the nitride-based phosphor may absorb a part of the wavelength-converted light by the aluminum / garnet phosphor, the nitride-based phosphor is an aluminum / garnet-based phosphor. It is preferable to laminate the wavelength conversion member so as to be disposed at a position closer to the light emitting element than the phosphor. By configuring in this way, a part of the light wavelength-converted by the aluminum / garnet phosphor is not absorbed by the nitride phosphor, and the aluminum / garnet phosphor and the nitride phosphor Compared to the case where an aluminum garnet phosphor is placed closer to the light emitting element than the nitride phosphor, and mixed color light due to light from both phosphors and the light emitting element. Can improve the color rendering.
(Alkaline earth metal salt)
  The light-emitting device in this embodiment mode uses alkaline earth activated by europium as a phosphor that absorbs part of light emitted from a light-emitting element and emits light having a wavelength different from the wavelength of the absorbed light. It can also have a metal silicate. The alkaline earth metal silicate is preferably an alkaline earth metal orthosilicate represented by the following general formula.
(2-xy) SrO.x (Ba, Ca) O. (1-abbcd) SiO₂・ AP₂O₅bAl₂O₃cB₂O₃dGeO₂: YEu²⁺(Where 0 <x <1.6, 0.005 <y <0.5, 0 <a, b, c, d <0.5).
(2-xy) BaO.x (Sr, Ca) O. (1-abbcd) SiO₂・ AP₂O₅bAl₂O₃cB₂O₃dGeO₂: YEu²⁺(In the formula, 0.01 <x <1.6, 0.005 <y <0.5, 0 <a, b, c, d <0.5.)
  Here, preferably, at least one of the values of a, b, c and d is greater than 0.01.
[0092]
  The light-emitting device in the present embodiment is a phosphor composed of an alkaline earth metal salt. In addition to the alkaline earth metal silicate described above, alkaline earth metal aluminate or Y activated by europium and / or manganese is used. (V, P, Si) O₄: Eu, or an alkaline earth metal-magnesium-disilicate represented by the following formula:
[0093]
  Me (3-xy) MgSi₂O₃: XEu, yMn (in the formula, 0.005 <x <0.5, 0.005 <y <0.5, Me represents Ba and / or Sr and / or Ca)
  Next, the manufacturing process of the phosphor made of alkaline earth metal silicate in the present embodiment will be described.
[0094]
  For the production of alkaline earth metal silicates, the stoichiometric amounts of the starting materials alkaline earth metal carbonate, silicon dioxide and europium oxide are intimately mixed according to the selected composition, and the phosphor is produced. In a conventional solid reaction, the desired phosphor is converted at a temperature of 1100 ° C. and 1400 ° C. under a reducing atmosphere. At this time, it is preferable to add less than 0.2 mol of ammonium chloride or other halide. If necessary, part of silicon can be replaced with germanium, boron, aluminum, and phosphorus, and part of europium can be replaced with manganese.
[0095]
  Phosphors as described above, ie alkaline earth metal aluminates and Y (V, P, Si) O activated with europium and / or manganese.₄: Eu, Y₂O₂S: Eu³⁺By combining one of these phosphors or these phosphors, an emission color having a desired color temperature and high color reproducibility can be obtained.
(Organic phosphor)
  In addition to the inorganic phosphor described above, an organic phosphor that can be uniformly dissolved in a sol solution of a light-transmitting inorganic member can also be used. Since most of the sol solution of the translucent inorganic member is composed of an organic substance, most of the organic phosphor is dissolved in the sol solution and becomes transparent. As an organic phosphor, for example, uniformly dissolved in a polysilazane solution (HFA)₃Tb (TPPO)₂Ya (HFA)₃Eu (TPPO)₂Can be mentioned. Where (HFA)₃Tb (TPPO)₂The structural formula is shown in [Chemical Formula 1] below.
[0096]
[Chemical 1]

[0097]
(HFA)₃Tb (TPPO)₂For example, terbium acetate is used as a starting material, and the central metal is Tb. Excited by light in the ultraviolet region, green light emission can be observed. In addition, the above (HFA)₃Eu (TPPO)₂Emits red light (HFA)₃Tb (TPPO)₂In addition, the wavelength conversion member can be made to emit white-color mixed light by including it in the wavelength conversion member together with other organic phosphors that emit green light. Unlike organic phosphors such as YAG phosphors and nitride phosphors described above, organic phosphors that are uniformly dissolved in the material of the translucent inorganic member can form a wavelength conversion member with a thin film. Yes, it can exist uniformly dispersed without settling in the wavelength conversion member. Furthermore, in the process of creating a protective film for the light emitting element, a wavelength conversion member that also functions as a protective film for the light emitting element can be formed on the surface of the light emitting element, and the process for forming the wavelength converting member can be simplified.
[Light emitting element]
  The light emitting element used in the present embodiment is, for example, an LED chip. When a light emitting device that emits light having a wavelength converted by exciting a phosphor by combining the phosphor and a light emitting element, an LED chip that emits light having a wavelength that can excite the phosphor is used. In the LED chip, a semiconductor such as GaAs, InP, GaAlAs, InGaAlP, InN, AlN, GaN, InGaN, AlGaN, or InGaAlN is formed as a light emitting layer on a substrate by MOCVD or the like. Examples of the semiconductor structure include a homostructure having a MIS junction, a PIN junction, a PN junction, etc., a heterostructure, or a double heterostructure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. In addition, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film in which a quantum effect is generated can be used. Preferably, a nitride compound semiconductor (general formula In) capable of efficiently emitting a relatively short wavelength capable of efficiently exciting the phosphor._iGa_jAl_kN, where 0 ≦ i, 0 ≦ j, 0 ≦ k, i + j + k = 1).
[0098]
  When a gallium nitride compound semiconductor is used, a material such as sapphire, spinel, SiC, Si, ZnO, or GaN is preferably used for the semiconductor substrate. In order to form gallium nitride with good crystallinity, it is more preferable to use a sapphire substrate. When a semiconductor film is grown on a sapphire substrate, it is preferable to form a gallium nitride semiconductor having a PN junction on a buffer layer made of GaN, AlN or the like. In addition, SiO on the sapphire substrate₂A GaN single crystal itself selectively grown using as a mask can also be used as a substrate. In this case, after forming each semiconductor layer, SiO₂It is also possible to separate the light emitting element and the sapphire substrate by etching away. Gallium nitride-based compound semiconductors exhibit N-type conductivity without being doped with impurities. When forming a desired N-type gallium nitride semiconductor such as improving luminous efficiency, Si, Ge, Se, Te, C, etc. are preferably introduced as appropriate as N-type dopants. On the other hand, when a P-type gallium nitride semiconductor is formed, a P-type dopant such as Zn, Mg, Be, Ca, Sr, or Ba is doped.
[0099]
  Since a gallium nitride compound semiconductor is difficult to be converted into a P-type simply by doping with a P-type dopant, it is preferable to make it P-type by annealing with heating in a furnace, low-energy electron beam irradiation, plasma irradiation, etc. after introduction of the P-type dopant. . Specific examples of the layer structure of the light-emitting element include an N-type contact layer, which is a gallium nitride semiconductor, and an aluminum nitride / gallium semiconductor on a sapphire substrate or silicon carbide having a buffer layer in which gallium nitride, aluminum nitride, or the like is formed at a low temperature. An N-type cladding layer, an active layer that is an indium gallium nitride semiconductor doped with Zn and Si, a P-type cladding layer that is an aluminum nitride-gallium semiconductor, and a P-type contact layer that is a gallium nitride semiconductor Are preferable. In order to form an LED chip, in the case of an LED chip having a sapphire substrate, an exposed surface of a P-type semiconductor and an N-type semiconductor is formed by etching or the like, and then a sputtering method or a vacuum evaporation method is used on the semiconductor layer. Each electrode having a desired shape is formed. In the case of a SiC substrate, a pair of electrodes can be formed using the conductivity of the substrate itself.
[0100]
  Next, the formed semiconductor wafer or the like is either fully cut directly by a dicing saw with a blade having a diamond cutting edge, or a groove having a width wider than the cutting edge width is cut (half cut), and then the semiconductor is applied by an external force. Break the wafer. Alternatively, after a very thin scribe line (meridian line) is drawn on the semiconductor wafer by, for example, a grid pattern by a scriber in which the diamond needle at the tip moves reciprocally linearly, the wafer is divided by an external force and cut into chips. In this way, the LED chip 102 which is a nitride compound semiconductor can be formed. Here, in this invention, it can cut especially after forming a wavelength conversion member. Since the optical characteristic of the mixed color light of the light emitting element and the light emitted from the light emitting element is wavelength-converted by the phosphor can be performed in a semiconductor wafer state, a light emitting device having a desired light emitting characteristic is formed with high yield. Can do.
[0101]
  In the light emitting device of the present invention that emits light by exciting the phosphor, the main emission wavelength of the LED chip is preferably 350 nm or more and 530 nm or less in consideration of the complementary color with the phosphor and the like.
[Conductive wire 911]
  As a fixing method of the light emitting element, at least one electrode of the light emitting element is opposed to the lead electrode and electrically connected through a conductive member, or the substrate side of the light emitting element is fixed with an adhesive and the electrode of the light emitting element is fixed. A method of connecting the lead electrode to the lead electrode with a conductive wire can be used. When the latter method is employed, for example, the light emitting element chip is die-bonded on one lead electrode with an epoxy resin or the like, and then each electrode of the light emitting element chip and the lead electrode are connected by a conductive wire. The conductive wire is required to have good ohmic properties with the electrodes of the LED chip, mechanical connectivity, electrical conductivity, and thermal conductivity. The thermal conductivity is 0.01 cal / (s) (cm²) (° C./cm) or more, more preferably 0.5 cal / (s) (cm²) (° C./cm) or more. In consideration of workability and the like, the diameter of the conductive wire is preferably Φ10 μm or more and Φ45 μm or less. In particular, the conductive wire is easily disconnected at the interface between the wavelength conversion member containing the phosphor and the mold member not containing the phosphor. Even if the same material is used, it is considered that wire breakage easily occurs because the substantial amount of thermal expansion differs depending on the phosphor. Therefore, the diameter of the conductive wire is more preferably 25 μm or more, and more preferably 35 μm or less from the viewpoint of light emitting area and ease of handling.
[0102]
  Specific examples of such conductive wires include conductive wires using metals such as gold, copper, platinum, and aluminum, and alloys thereof. Such a conductive wire can easily connect the electrode of each LED chip to the inner lead, the mount lead, and the like by a wire bonding device.
[Mold member]
  The mold member can be provided to protect the LED chip, the conductive wire, the wavelength conversion member, and the like from the external environment according to the use of the light emitting diode. In general, the mold member can be formed using a resin. Moreover, although a viewing angle can be increased by containing fluorescent substance, the directivity from an LED chip can be eased and the viewing angle can be further increased by adding a diffusing agent to the resin mold. Furthermore, by forming the mold member in a desired shape, it is possible to have a lens effect that focuses or diffuses light emitted from the LED chip. Accordingly, a plurality of mold members may be stacked. Specifically, a convex lens shape, a concave lens shape, an elliptical shape as viewed from the light emission observation surface, or a combination of them. As a specific material of the mold member, a transparent resin or glass having excellent weather resistance such as an epoxy resin, a urea resin, or a silicone resin is preferably used. In particular, when the mold member is formed of the above-described glassy translucent inorganic member, it can be formed by adjusting the viscosity of the sol solution. As the diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide, silicon dioxide, or the like is preferably used. Furthermore, in addition to the diffusing agent, a phosphor can also be contained in the mold member. Therefore, the phosphor may be used in the mold member or in other wavelength conversion members. Further, the wavelength conversion member may be formed of a light-transmitting inorganic member containing a phosphor, and the mold member may be formed of a material different from that of a light-transmitting resin. In this case, a light-emitting device with high productivity and less influence of moisture or the like can be obtained. In consideration of reducing the difference in refractive index, the mold member and the wavelength conversion member may be formed using the same material. In the present invention, adding a diffusing agent or a coloring agent to the mold member can hide the coloring of the phosphor viewed from the light emission observation surface side. In addition, the coloring of the phosphor means that the phosphor of the present invention emits light by absorbing the blue component of the strong external light. Therefore, it seems to be colored yellow. In particular, depending on the shape of the mold member such as a convex lens shape, the colored portion may appear enlarged. Such coloring may be undesirable in terms of design. The diffusing agent contained in the mold member can make the mold member invisible white by coloring the mold member milky white and the colorant in a desired color. Therefore, the color of the phosphor is not observed from such a light emission observation surface side.
[0103]
  Moreover, when the main light emission wavelength of the light emitted from the LED chip is 430 nm or more, it is more preferable in terms of weather resistance to contain an ultraviolet absorber as a light stabilizer in the mold member.
  Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.
[0104]
[Example 1]
FIG. 1 is a schematic cross-sectional view of a light emitting device according to this example, and FIG. 2 schematically shows a method for forming a wavelength conversion member according to this example by stencil printing.
[0105]
  As shown in FIG. 1, in the light emitting device according to this example, a wavelength conversion member 101 is formed on the surface of a sapphire substrate 102 of an LED chip 100 that is a light emitting device. The LED chip 100 has a 475 nm In as a light emitting layer with a monochromatic emission peak of visible light._0.2Ga_0.8A nitride semiconductor light emitting device having an N semiconductor is used. More specifically, the LED chip 100 flows TMG (trimethylgallium) gas, TMI (trimethylindium) gas, nitrogen gas, and a dopant gas together with a carrier gas onto a cleaned sapphire substrate, and a nitride semiconductor is formed by MOCVD. It can be formed by forming a film. SiH as dopant gas₄And Cp₂A layer to be an n-type nitride semiconductor or a p-type nitride semiconductor is formed by switching Mg.
[0106]
  The element structure of the LED chip 100 includes an n-type GaN layer that is an undoped nitride semiconductor on a sapphire substrate 102, a GaN layer that is formed with an Si-doped n-type electrode and serves as an n-type contact layer, and an undoped nitride semiconductor. N-type GaN layer, GaN layer to be the next light-emitting layer, InGaN layer to form the well layer, and five GaN layers sandwiched between the GaN layers as a set of GaN layers to be the barrier layer It is a stacked multiple quantum well structure. On the light emitting layer, an AlGaN layer as a p-type cladding layer doped with Mg and a GaN layer as a p-type contact layer doped with Mg are sequentially laminated. (A GaN layer is formed on the sapphire substrate 102 at a low temperature to serve as a buffer layer. The p-type semiconductor is annealed at 400 ° C. or higher after film formation.) Next, the sapphire substrate is etched. The surface of each pn contact layer is exposed on the same side as the nitride semiconductor on 102. Positive and negative pedestal electrodes are formed on each contact layer by sputtering. In addition, after forming a metal thin film as a translucent electrode on the entire surface of the p-type nitride semiconductor, a base electrode is formed on a part of the translucent electrode.
[0107]
  Next, a fluorescent material to be dispersed and contained in the wavelength conversion member 101 is formed. As the fluorescent material in this embodiment, mixed raw materials are obtained by mixing respective oxides of Y, Gd, Al, and Ce at a stoichiometric ratio. This is mixed with flux and packed in a crucible and mixed for 2 hours in a ball mill mixer. After the balls are removed, baking is performed at 1400 ° C. to 1600 ° C. for 6 hours in a weak reducing atmosphere, and further baking is performed at 1400 ° C. to 1600 ° C. for 6 hours in a reducing atmosphere. The fired product is ball-milled in water, washed, separated, dried, and finally passed through a sieve to have a center particle size of 8 μm (Y_0.8Gd_0.2)_2.750Al₅O₁₂: Ce_0.250Form a fluorescent material.
[0108]
  The viscosity of a mixed solution in which 150 parts by weight of the fluorescent material is added to 100 parts by weight of an alumina sol solution to which nitric acid is added as a stabilizer is adjusted so that the phosphor is uniformly dispersed in the mixed solution.
[0109]
  A stainless steel stencil is arranged on the substrate surface side of the semiconductor wafer. At this time, the stencil masks the scribe line formation position on the upper surface of the substrate so that the stencil can be divided into each light emitting device in a later process, and a through hole in which a part of the substrate surface of the light emitting device is exposed. Is provided in a mesh shape. After disposing the stencil, the mixed solution is filled into the through holes of the stencil to perform stencil printing and to dry. Drying is performed at room temperature for 1 hour, at a temperature of 100 ° C. for 10 minutes, and at a temperature of 200 ° C. to 250 ° C. for 30 minutes. By performing such drying, it is possible to prevent the wavelength conversion member from cracking. Moreover, sufficient adhesive force on the sapphire substrate can be given to the wavelength conversion member.
[0110]
  Finally, the alumina sol solution containing the phosphor is cured, and the wavelength conversion member 101 having a uniform film thickness of several tens of μm is formed on the upper surface of the sapphire substrate 102 of the light emitting element according to the emission observation direction.
[0111]
  After a scribe line is drawn on the semiconductor wafer having the wavelength conversion member 101 laminated on the upper surface of the sapphire substrate 102, the light emitting element is divided by an external force. Thus, the light emitting element in which the wavelength conversion member is formed can emit mixed color light of the light from the light emitting layer and the light whose wavelength is converted by the phosphor from the sapphire substrate side.
[0112]
  Finally, the electrodes 104 and 105 of the light emitting element 100 on which the wavelength conversion member 101 is formed are opposed to the conductive pattern provided on the mounting substrate, and are electrically connected by the conductive member. Further, the light emitting device is formed by covering the light emitting element 100 and the wavelength conversion member 101 with resin.
[0113]
  In the light emitting device of the present embodiment formed as described above, a part of the light emitted from the LED chip is wavelength-converted by the fluorescent material contained in the wavelength conversion member, and the mixed color light emitted from the mold member depends on the observation direction. Observed uniformly. In addition, since the light-transmitting inorganic member is formed with a thickness that is difficult to break, a highly reliable light-emitting device can be obtained.
[Example 2]
In this example, as shown in FIGS. 3 and 4, a nitride-based phosphor (Sr_0.7Ca_0.3)₂Si₅N₈: After forming a wavelength conversion member containing Eu, a YAG-based phosphor is formed on the wavelength conversion member in the same manner as in Example 1 (Y_0.8Gd_0.2)_2.750Al₅O₁₂: Ce_0.250A wavelength conversion member containing a fluorescent material is formed. Here, the nitride phosphor has a wide absorption spectrum region in the peak wavelength region of the emission spectrum of the YAG phosphor.
[0114]
  First, a nitride-based phosphor (Sr_0.7Ca_0.3)₂Si₅N₈: Stencil printing is performed on the substrate side of the semiconductor wafer using an Eu-containing alumina sol solution as a material. At this time, the first stencil 111 for forming the wavelength conversion member containing the nitride phosphor masks the scribe line formation position on the upper surface of the substrate in order to facilitate division for each light emitting element, In addition, a through hole is provided so that a part of the substrate surface of the light emitting element is exposed. After forming the wavelength conversion member 101 containing the nitride phosphor, the first stencil 111 is placed as it is, and the second stencil 112 is placed in the same state as the first stencil 111 and the through hole. It is arranged on the stencil 111. Next, on the wavelength conversion member 101 containing the nitride phosphor (Y_0.8Gd_0.2)_2.750Al₅O₁₂: Ce_0.250A wavelength conversion member 103 containing a fluorescent material is formed. After the wavelength conversion member 103 is formed, the first stencil plate 111 and the second stencil plate 112 are removed, and the light emitting device 200 as shown in FIG. 3 can be obtained by cutting each light emitting device.
[0115]
  Finally, the electrodes 104 and 105 of the light emitting element 200 on which the wavelength conversion member is formed are opposed to the conductive pattern provided on the mounting substrate and electrically connected. Further, the light emitting device is formed by covering the light emitting element 200 and the wavelength conversion members 101 and 103 with resin.
[0116]
  By combining a plurality of phosphors in this way, light converted in wavelength by the YAG phosphor is not absorbed by the nitride phosphor, improving the color rendering of the light mixture of the light emitting element and the phosphor. The light emitting device can be made. In addition, since the light-transmitting inorganic member is formed with a thickness that is difficult to break, a highly reliable light-emitting device can be obtained.
[Example 3]
FIG. 5 is a cross-sectional view schematically showing the light emitting device 300 according to this example. A mask is applied to the position where the electrode of the light emitting element is formed, and stencil printing is performed in the same manner as in the other embodiments, so that the emission observation direction is relative to the surface where the electrode of the light emitting element is formed and the side end face. To form a wavelength conversion member having a uniform film thickness. The light emitting device is formed by connecting the electrode of the light emitting element and the lead electrode with a conductive wire, and covering the wavelength conversion member, the light emitting element, and the conductive wire with a mold member. By adopting the configuration of this embodiment, a light emitting device in which the mixed color light of the light emitting element and the phosphor is uniformly observed in the direction of the light emission observation surface can be obtained. In addition, since the light-transmitting inorganic member is formed with a thickness that is difficult to break, a highly reliable light-emitting device can be obtained.
[Example 4]
9 to 18 are cross-sectional views schematically showing manufacturing steps of the light emitting device 910 according to this example. A light emitting element 910 having a wavelength conversion member 101 as shown in FIG. 18 is created. Hereinafter, a method for forming the light-emitting element 910 will be described in the order of steps with reference to FIGS.
[0117]
  A conductive member 901 is disposed on the surface of the submount substrate 902 (FIG. 9), and a conductive pattern having an insulating portion 904 that separates the positive electrode and the negative electrode is formed (FIG. 10).
[0118]
  The material of the submount substrate 902 is preferably aluminum nitride with respect to a semiconductor light emitting element having substantially the same thermal expansion coefficient, for example, a nitride semiconductor light emitting element. By using such a material, thermal stress generated between the submount substrate 902 and the light emitting element 900 can be reduced. Alternatively, the material of the submount substrate 901 can be formed as a protective element having a p-type semiconductor region and an n-type semiconductor region, and silicon that has relatively high heat dissipation and is inexpensive is preferable. The conductive member 901 is preferably made of silver, gold, or aluminum with high reflectivity.
[0119]
  In order to improve the reliability of the light emitting device, an underfill material 905 is filled in a gap generated between the positive and negative electrodes of the light emitting element 900 and the insulating portion 904. First, an underfill material 905 is disposed around the insulating portion 904 of the submount substrate 902 (FIG. 11). The underfill material 905 is a thermosetting resin such as a silicone resin or an epoxy resin. In order to relieve the thermal stress of the underfill material 905, aluminum nitride, aluminum oxide, a composite mixture thereof, or the like may be further mixed into the epoxy resin. The amount of underfill is an amount that can fill a gap formed between the positive and negative electrodes of the light emitting element and the submount substrate 902.
[0120]
  Both the positive and negative electrodes of the light emitting element 900 are opposed to the positive and negative electrodes of the conductive pattern provided on the submount substrate 902, and are bonded and fixed by bumps 906 (FIG. 12). When the submount is a protective element, the positive electrode and the negative electrode of the light emitting element are connected to the n-type semiconductor region and the p-type semiconductor region of the protective element, respectively. First, bumps 906 that are conductive members are formed on both positive and negative electrodes of the light emitting element. Note that bumps 906 may be formed on both the positive and negative electrodes of the conductive pattern of the submount substrate 902. When the underfill material 905 disposed near the insulating portion 904 of the submount substrate 902 is softened (FIG. 11), the positive and negative electrodes of the light emitting element 900 are connected to the positive and negative electrodes of the conductive pattern via the bump 906. Opposed. Next, the positive and negative electrodes of the light-emitting element, the bump 906, and the conductive pattern are thermocompression bonded by load, heat, and ultrasonic waves. At this time, underfill between the bump 906 and the positive and negative electrodes of the conductive pattern is eliminated, and the electrode of the light emitting element and the conductive pattern are connected. The material of the bump 906 that is a conductive member is, for example, Au, eutectic solder (Au—Sn), Pb—Sn, lead-free solder, or the like.
[0121]
  A screen plate 907 is arranged from the substrate side of the light emitting element (FIG. 13). Instead of the screen plate 907, a metal mask may be disposed at a position where the wavelength conversion member 101 is not formed, such as a ball bonding position or a parting line formation position of the conductive wire 911.
[0122]
  A material in which a phosphor is contained in thixotropic alumina sol is prepared, and screen printing is performed using a squeegee 908 (FIG. 14).
[0123]
  When the screen plate 907 is removed (FIG. 15), the phosphor-containing material is cured (FIG. 16), and cut for each light emitting element along the parting line (FIG. 17), light emission having the wavelength conversion member 101 Element 910 is completed (FIG. 18).
[0124]
  Further, as shown in FIGS. 19, 20, and 21 (cross-sectional view taken along line AA ′ in FIG. 20), the light emitting element 910 is fixed to the recess bottom surface 913 of the package 912 using Ag paste as an adhesive. A light emitting device can be obtained by connecting the lead electrode 914 partially exposed to the bottom surface 913 of the concave portion 911 and the conductive pattern provided on the submount substrate 902. Here, in the light emitting device in this embodiment, the lens 915 for controlling the light distribution of the light emitting device and the heat dissipation of the light emitting element are improved, and the concave bottom surface for mounting the light emitting element is partially formed. A metal substrate 916 to be processed. In addition, a mold member such as a silicone resin is preferably disposed in the gap between the lower surface of the lens 915 and the inner wall surface of the recess of the package 912. With such a structure, extraction of light from the light-emitting element can be improved and a highly reliable light-emitting device can be obtained.
[0125]
  In the light emitting device according to the present embodiment, the content and distribution of the fluorescent material contained in the wavelength conversion member are almost uniform, and variations in optical characteristics such as chromaticity and light amount are unlikely to occur among the light emitting devices. In addition, a desired light-emitting device can be uniformly formed without causing waste in the light-emitting device formation process and the components of the light-emitting device, which is excellent in mass productivity.
[Example 5]
FIG. 7 is a schematic cross-sectional view of the light emitting device according to this example. As shown in FIG. 7, the laminate of wavelength conversion members according to this example has a first layer 701, a second layer 702, and a refractive index different from those of the second layer from the light emitting element side. A third layer 703 is sequentially stacked with respect to the light emitting element. The first layer 701 is a translucent inorganic member (refractive index; n₁= 1.8) a nitride-based phosphor is bound. The first layer 701 is formed as a collection of dots having a bullet-shaped lens shape and arranged in a large number of stripes, lattices, or concentric circles on the substrate side of the light emitting element. The second layer 702 includes a translucent inorganic member (refractive index; n₂= 1.8), and the third layer 703 is a translucent inorganic member (refractive index; n) mainly composed of alumina.₃= 1.7), an aluminum garnet phosphor is bound. Furthermore, the first layer 701 in the laminate of wavelength conversion members according to the present example is such that the light whose wavelength has been converted by the first layer 701 is entirely at the interface between the second layer 702 and the third layer 703. It has a lens shape that is optically controlled so as to travel in a non-reflecting direction. That is, the light emitted from the first layer 701 is the critical angle θ at the interface formed by the second layer 702 and the third layer 703.₀(Θ₀= Sin^-1n₃/ N₂= Sin^-10.94) The traveling direction is controlled so as to enter the interface at a smaller angle. Therefore, the light emitted from the substrate 102 side of the light emitting element (refractive index 2.5) is wavelength-converted by the nitride-based phosphor contained in the first layer 701, and the wavelength-converted light is The light is emitted and observed from the direction of the emission observation surface without being totally reflected at the interface between the second layer 702 and the third layer 703.
[0126]
  With this configuration, light emitted from the first layer 701 is not totally reflected at the interface between the second layer 702 and the third layer 702, and is in a direction different from the direction of the emission observation surface. Since the progress is suppressed, the extraction efficiency of the wavelength-converted light can be improved.
[0127]
【The invention's effect】
  INDUSTRIAL APPLICABILITY The present invention can easily obtain a light emitting device having a uniform phosphor content and distribution with a good production yield. When the wavelength conversion member is formed using a relatively fragile translucent inorganic member such as glass, the translucent inorganic member can be easily formed to a thickness that is difficult to break. In addition, since the content and distribution of the fluorescent substance contained in the wavelength conversion member are almost uniform, variations in optical properties such as chromaticity and light quantity are less likely to occur among light emitting devices, and the manufacturing yield of light emitting devices is improved. To do. In addition, by mixing multiple types of phosphors with different excitation absorption spectra and emission spectra, by forming a multi-layered wavelength conversion member that contains multiple types of phosphors, the color rendering of the mixed color light emitted from the light emitting device Property can be improved. In addition, a desired light-emitting device can be formed with good workability without causing waste in the process and the components of the light-emitting device.
[0128]
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a light emitting device according to an embodiment of the present invention.
FIG. 2 is a schematic view showing a method for forming a wavelength conversion member according to an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view of a light emitting device according to an example of the present invention.
FIG. 4 is a schematic view showing a method for forming a wavelength conversion member according to an embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view of a light emitting device according to an example of the present invention.
FIG. 6 is a schematic top view of a light emitting device according to an example of the present invention.
FIG. 7 is a schematic cross-sectional view of a light emitting device according to an example of the present invention.
FIG. 8 is a schematic cross-sectional view of a light emitting device according to an example of the present invention.
FIG. 9 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 10 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 11 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 12 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 13 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 14 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 15 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 16 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 17 is a schematic cross-sectional view showing a forming process according to an embodiment of the present invention.
FIG. 18 is a schematic cross-sectional view showing a forming process according to an example of the present invention.
FIG. 19 is a schematic cross-sectional view of a light emitting device according to an example of the present invention.
FIG. 20 is a schematic top view of a light emitting device according to an example of the present invention.
FIG. 21 is a schematic cross-sectional view of a light emitting device according to an example of the present invention.
FIG. 22 is a schematic top view of a light emitting device according to an example of the present invention.
[Explanation of symbols]
100, 200, 300, 900, 131 ... light emitting element, 101, 103, 132 ... wavelength conversion member, 102 ... semiconductor light emitting element substrate, 104 ... positive electrode, 105 ... negative electrode, 106 ... stencil, 107 ... translucent inorganic member, 108 ... spatula, 109 ... phosphor, 110 ... side wall to be used as a mask, 111 ... first stencil, 112 ... Second stencil, 701, 801 ... first layer, 702 ... second layer, 703 ... third layer, 901 ... conductive member, 902 ... submount substrate 903 ... Parting line 904 ... Insulating part 905 ... Underfill material 906 ... Bump 907 ... Screen plate 908 ... Squeegee 909 ... Wavelength conversion member 910 ... Wavelength conversion member The formed light-emitting element, 911 ... conductive wire, 912 ... package 913 ... recess bottom surface, 914 ... lead electrodes, 915 ... lens, 916 ... metal substrate.

Claims (1)

A light emitting device comprising: a light emitting element; and a wavelength conversion member that emits different wavelengths by absorbing light of the light emitting element,
The wavelength conversion member is composed of a translucent inorganic member and a phosphor, and has a refractive index smaller than that of at least the first layer, the second layer, and the second layer in order from the light emitting element side. The third layer is laminated,
The first layer is a set of dots having a bullet-shaped lens shape that allows emitted light to enter the interface at an angle smaller than a critical angle at the interface between the second layer and the third layer. A light-emitting device arranged as a body on the light-emitting element .

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